Methods and systems for treatment of lime to form vaterite

ABSTRACT

Provided herein are methods and systems to form calcium carbonate comprising vaterite, comprising dissolving lime in an aqueous base solution under one or more precipitation conditions to produce a precipitation material comprising calcium carbonate and a supernatant solution, wherein the calcium carbonate comprises vaterite.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of U.S. Provisional Application No.62/981,266, filed Feb. 25, 2020, which is incorporated herein byreference in its entirety in the present disclosure.

BACKGROUND

Carbon dioxide (CO₂) emissions have been identified as a majorcontributor to the phenomenon of global warming. CO₂ is a by-product ofcombustion and it creates operational, economic, and environmentalproblems. It may be expected that elevated atmospheric concentrations ofCO₂ and other greenhouse gases can facilitate greater storage of heatwithin the atmosphere leading to enhanced surface temperatures and rapidclimate change. In addition, elevated levels of CO₂ in the atmospheremay also further acidify the world's oceans due to the dissolution ofCO₂ and formation of carbonic acid. The impact of climate change andocean acidification may likely be economically expensive andenvironmentally hazardous if not timely handled. Reducing potentialrisks of climate change requires sequestration and avoidance of CO₂ fromvarious anthropogenic processes.

SUMMARY

In one aspect, there are provided methods to form calcium carbonatecomprising vaterite, comprising:

(i) calcining limestone to form lime and a gaseous stream comprisingcarbon dioxide;

(ii) dissolving the lime in an aqueous N-containing inorganic saltsolution under one or more dissolution conditions to produce a firstaqueous solution comprising calcium salt, and a gaseous streamcomprising ammonia;

(iii) recovering the gaseous stream comprising carbon dioxide and thegaseous stream comprising ammonia and subjecting the gaseous streams toa cooling process under one or more cooling conditions to condense asecond aqueous solution comprising ammonium bicarbonate, ammoniumcarbonate, ammonia, or combinations thereof; and

(iv) treating the first aqueous solution comprising calcium salt withthe second aqueous solution comprising ammonium bicarbonate, ammoniumcarbonate, ammonia, or combinations thereof under one or moreprecipitation conditions to form a precipitation material comprisingcalcium carbonate and a supernatant solution, wherein the calciumcarbonate comprises vaterite.

In some embodiments of the foregoing aspect, the calcination is carriedout in shaft kiln, rotary kiln, or electric kiln.

In some embodiments of the foregoing aspect and embodiments, the lime isunderburnt lime, soft burnt lime, dead burnt lime, or combinationsthereof.

In some embodiments of the foregoing aspect and embodiments, theN-containing inorganic salt is selected from the group consisting ofammonium halide, ammonium sulfate, ammonium sulfite, ammonium nitrate,ammonium nitrite, and combinations thereof. In some embodiments of theforegoing aspect and embodiments, the ammonium halide is ammoniumchloride.

In some embodiments of the foregoing aspect and embodiments, the firstaqueous solution further comprises ammonia and/or N-containing inorganicsalt.

In some embodiments of the foregoing aspect and embodiments, molar ratioof the N-containing inorganic salt:lime is between about 0.5:1-2:1.

In some embodiments of the foregoing aspect and embodiments, the one ormore dissolution conditions are selected from the group consisting oftemperature between about 30-200° C.; pressure between about 0.1-10 atm;N-containing salt wt % in water between about 0.5-50%; and combinationsthereof.

In some embodiments of the foregoing aspect and embodiments, no externalsource of carbon dioxide and/or ammonia is used and the process is aclosed loop process.

In some embodiments of the foregoing aspect and embodiments, the gaseousstream comprising ammonia further comprises water vapor.

In some embodiments of the foregoing aspect and embodiments, the gaseousstream further comprises between about 20-90% water vapor.

In some embodiments of the foregoing aspect and embodiments, no externalwater is added to the cooling process.

In some embodiments of the foregoing aspect and embodiments, the one ormore cooling conditions comprise temperature between about 0-100° C.;pressure between about 0.5-50 atm; pH of the aqueous solution betweenabout 8-12; flow rate of the CO₂; ratio of CO₂:NH₃ between about0.1:1-20:1; or combinations thereof.

In some embodiments of the foregoing aspect and embodiments, the secondaqueous solution further comprises ammonium carbamate.

In some embodiments of the foregoing aspect and embodiments, the secondaqueous solution is formed by the condensation of the gases.

In some embodiments of the foregoing aspect and embodiments, the one ormore precipitation conditions are selected from the group consisting ofpH of the first aqueous solution of between 7-9, temperature of thesolution between 20-60° C., residence time of between 5-60 minutes, orcombinations thereof.

In some embodiments of the foregoing aspect and embodiments, the firstaqueous solution further comprises solids.

In some embodiments of the foregoing aspect and embodiments, the methodfurther comprises separating the solids from the first aqueous solutionbefore the treatment step by filtration and/or centrifugation.

In some embodiments of the foregoing aspect and embodiments, theseparated solids are added to the precipitation material as filler.

In some embodiments of the foregoing aspect and embodiments, theseparated solids further comprise residual ammonium halide when theN-containing inorganic salt is the ammonium halide.

In some embodiments of the foregoing aspect and embodiments, the methodfurther comprises recovering the residual ammonium halide from thesolids using a recovery process selected from the group consisting ofrinsing, thermal decomposition, pH adjustment, and combinations thereof.

In some embodiments of the foregoing aspect and embodiments, the solidsare not separated from the first aqueous solution and the first aqueoussolution is subjected to the treatment step to produce the precipitationmaterial further comprising the solids. In some embodiments of theforegoing aspect and embodiments, the solids comprise silicates, ironoxides, alumina, or combinations thereof. In some embodiments of theforegoing aspect and embodiments, the solids are between 1-40 wt % inthe aqueous solution, in the precipitation material, or combinationsthereof.

In some embodiments of the foregoing aspect and embodiments, the methodfurther comprises dewatering the precipitation material to separate theprecipitation material from the supernatant solution.

In some embodiments of the foregoing aspect and embodiments, theprecipitation material and the supernatant solution comprise residualN-containing inorganic salt.

In some embodiments of the foregoing aspect and embodiments, theresidual N-containing inorganic salt comprises ammonium halide, ammoniumsulfate, ammonium sulfite, ammonium hydrosulfide, ammonium thiosulfate,ammonium nitrate, ammonium nitrite, or combinations thereof.

In some embodiments of the foregoing aspect and embodiments, the methodfurther comprises removing and optionally recovering ammonia and/orN-containing inorganic salt from the residual N-containing inorganicsalt comprising removing and optionally recovering the residualN-containing inorganic salt from the supernatant aqueous solution and/orremoving and optionally recovering the residual N-containing inorganicsalt from the precipitation material.

In some embodiments of the foregoing aspect and embodiments, the methodfurther comprises recovering the residual N-containing inorganic saltfrom the supernatant aqueous solution using recovery process selectedfrom the group consisting of thermal decomposition, pH adjustment,reverse osmosis, multi-stage flash, multi-effect distillation, vaporrecompression, distillation, and combinations thereof.

In some embodiments of the foregoing aspect and embodiments, the step ofremoving and optionally recovering the residual N-containing inorganicsalt from the precipitation material comprises heating the precipitationmaterial between about 300-360° C. to evaporate the N-containinginorganic salt from the precipitation material with optional recovery bycondensation of the N-containing inorganic salt.

In some embodiments of the foregoing aspect and embodiments, theN-containing inorganic salt is ammonium chloride which evaporates fromthe precipitation material in a form comprising ammonia gas, hydrogenchloride gas, chlorine gas, or combinations thereof.

In some embodiments of the foregoing aspect and embodiments, the methodfurther comprises recycling the recovered residual ammonia and/orN-containing inorganic salt back to the dissolving and/or treating stepof the process.

In some embodiments of the foregoing aspect and embodiments, thevaterite is stable vaterite or reactive vaterite.

In some embodiments of the foregoing aspect and embodiments, the methodfurther comprises adding water to the precipitation material comprisingreactive vaterite and transforming the vaterite to aragonite wherein thearagonite sets and hardens to form cement or cementitious product.

In some embodiments of the foregoing aspect and embodiments, thecementitious product is a formed building material selected from masonryunit, construction panel, conduit, basin, beam, column, slab, acousticbarrier, insulation material, and combinations thereof.

In some embodiments of the foregoing aspect and embodiments, the methodfurther comprises adding water to the precipitation material comprisingreactive vaterite and transforming the vaterite to aragonite wherein thearagonite sets and hardens to form non-cementitious product.

In one aspect, there is provided a product formed by the methodaccording to the aforementioned aspect and the embodiments.

In one aspect, there is provided a system to form calcium carbonatecomprising vaterite, comprising:

(i) a calcining reactor configured to calcine limestone to form lime anda gaseous stream comprising carbon dioxide;

(ii) a dissolution reactor configured for dissolving the lime in anaqueous N-containing inorganic salt solution under one or moredissolution conditions to produce a first aqueous solution comprisingcalcium salt, and a gaseous stream comprising ammonia;

(iii) a cooling reactor configured for recovering the gaseous streamcomprising carbon dioxide and the gaseous stream comprising ammonia andsubjecting the gaseous streams to a cooling process under one or morecooling conditions to condense a second aqueous solution comprisingammonium bicarbonate, ammonium carbonate, ammonia, or combinationsthereof; and

(iv) a treatment reactor configured for treating the first aqueoussolution comprising calcium salt with the second aqueous solutioncomprising ammonium bicarbonate, ammonium carbonate, ammonia, orcombinations thereof under one or more precipitation conditions to forma precipitation material comprising calcium carbonate and a supernatantsolution, wherein the calcium carbonate comprises vaterite.

In some embodiments of the foregoing aspect, the dissolution reactor isintegrated with the cooling reactor.

DRAWINGS

The features of the invention are set forth with particularity in theappended claims. A better understanding of the features and advantagesof the invention will be obtained by reference to the following detaileddescription that sets forth illustrative embodiments, in which theprinciples of the invention are utilized, and the accompanying drawingsof which:

FIG. 1 illustrates some embodiments of the methods and systems providedherein.

FIG. 2 illustrates some embodiments of the methods and systems providedherein.

FIG. 3 illustrates some embodiments of the methods and systems providedherein.

FIG. 4 illustrates some embodiments of the methods and systemscomprising an integrated reactor provided herein.

FIG. 5 illustrates some embodiments of the methods and systemscomprising an integrated reactor provided herein.

FIG. 6 illustrates some embodiments of the methods and systemscomprising an integrated reactor provided herein.

FIG. 7 illustrates some embodiments of the methods and systemscomprising an integrated reactor provided herein.

FIG. 8 illustrates a Gibbs free energy diagram of the transition fromvaterite to aragonite.

FIG. 9 illustrates the effects of CO₂:NH₃ ratio on the formation and theratio of the condensed products in the cooling reactor, as described inExample 4 herein.

DESCRIPTION

Provided herein are unique methods and systems that use the lime to formthe vaterite polymorph of calcium carbonate which can be used to formvarious products as described herein. The lime is obtained from thecalcination of the limestone. Applicants have devised unique methods andsystems to use the lime to form valuable cementitious products. In someembodiments of the methods and systems provided herein, the lime istreated directly with an aqueous base solution, such as for exampleonly, ammonium salt e.g. aqueous ammonium chloride solution, tosolubilize or dissolve calcium of the lime in an aqueous solution. Thedissolved calcium in the form of calcium salt is then treated with thecarbon dioxide gas (evolved during the calcination of the limestone) toform precipitate or precipitation material comprising calcium carbonatewhich is partially or fully in vaterite polymorphic form.

In some embodiments, the calcium carbonate is formed in vateritepolymorphic form or in some embodiments the calcium carbonate isprecipitated calcium carbonate (PCC). The PCC can be in the form ofvaterite, aragonite, calcite, or combinations thereof. In someembodiments, the vaterite formed by the methods and systems herein, isin stable vaterite form or is in a reactive vaterite form, both of whichhave been described herein. In some embodiments, the precipitationmaterial comprising reactive vaterite possesses unique properties,including, but not limited to, cementing properties by transforming toaragonite which sets and cements with high compressive strength. In someembodiments, the vaterite transformation to aragonite results in cementthat can be used to form building materials and/or cementitious productssuch as, but not limited to, formed building materials such asconstruction panel etc. further described herein. In some embodiments,the vaterite in the product is stable (does not transform to aragonite)and may be used as a filler or supplementary cementitious material (SCM)when mixed with other cement such as Ordinary Portland Cement (OPC). Theprecipitation material comprising vaterite may also be used as anaggregate where the reactive vaterite containing precipitation materialafter contact with water transforms to aragonite, which sets and cementsand which is then chopped up after cementation to form the aggregate. Insome embodiments, where the calcium carbonate is formed as PCC, the PCCmaterial is cementitious or may be used as a filler in products such aspaper product, polymer product, lubricant, adhesive, rubber product,chalk, asphalt product, paint, abrasive for paint removal, personal careproduct, cosmetic, cleaning product, personal hygiene product,ingestible product, agricultural product, soil amendment product,pesticide, environmental remediation product, and combination thereof.Such use of calcium carbonate precipitation material as a filler innon-cementitious products has been described in U.S. Pat. No. 7,829,053,issued Nov. 9, 2010, which is incorporated herein by reference in itsentirety.

The base, such as but not limited to, N-containing inorganic salt or theN-containing organic salt, for example only, an ammonium salt, used tosolubilize the calcium ions from the lime, may result in residualN-containing inorganic salt or N-containing organic salt remaining inthe supernatant solution as well as in the precipitate itself after theformation of the precipitate. In some embodiments, the presence of theN-containing inorganic salt or the N-containing organic salt in theprecipitate may not be desirable as the N-containing inorganic salt orthe N-containing organic salt content such as but not limited to,ammonium chloride, ammonium sulfate, ammonium sulfite, ammoniumhydrosulfide, ammonium thiosulfate, ammonium nitrate, ammonium nitrite,or combinations thereof content, in the precipitate may be detrimentalto the cementitious products thus formed from the precipitationmaterial. For example, chloride in the cementitious product may becorrosive to metal structures that are used along with the cementitiousproducts. Further, the residual ammonia may add to the foul smell in theproducts. Furthermore, the non-recovered and wasted residualN-containing inorganic salt or N-containing organic salt in theprecipitate as well as the supernatant solution may be economically aswell as environmentally not feasible. Various methods have been providedherein to remove and optionally recover the N-containing inorganic saltor the N-containing organic salt from the supernatant solution as wellas the precipitate.

Before the invention is described in greater detail, it is to beunderstood that this invention is not limited to particular embodimentsdescribed, as such may, of course, vary. It is also to be understoodthat the terminology used herein is for the purpose of describingparticular embodiments only, and is not intended to be limiting.

Where a range of values is provided, it is understood that eachintervening value, to the tenth of the unit of the lower limit unlessthe context clearly dictates otherwise, between the upper and lowerlimit of that range and any other stated or intervening value in thatstated range, is encompassed within the invention. The upper and lowerlimits of these smaller ranges may independently be included in thesmaller ranges and are also encompassed within the invention, subject toany specifically excluded limit in the stated range. Where the statedrange includes one or both of the limits, ranges excluding either orboth of those included limits are also included in the invention.

Certain ranges are presented herein with numerical values being precededby the term “about.” The term “about” is used herein to provide literalsupport for the exact number that it precedes, as well as a number thatis near to or approximately the number that the term precedes. Indetermining whether a number is near to or approximately a specificallyrecited number, the near or approximating unrequited number may be anumber, which, in the context in which it is presented, provides thesubstantial equivalent of the specifically recited number.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs. Although any methods andmaterials similar or equivalent to those described herein can also beused in the practice or testing of the invention, representativeillustrative methods and materials are described herein.

All publications, patents, and patent applications cited in thisspecification are incorporated herein by reference to the same extent asif each individual publication, patent, or patent application werespecifically and individually indicated to be incorporated by reference.Furthermore, each cited publication, patent, or patent application isincorporated herein by reference to disclose and describe the subjectmatter in connection with which the publications are cited. The citationof any publication is for its disclosure prior to the filing date andshould not be construed as an admission that the invention describedherein is not entitled to antedate such publication by virtue of priorinvention. Further, the dates of publication provided may be differentfrom the actual publication dates, which may need to be independentlyconfirmed.

It is noted that, as used herein and in the appended claims, thesingular forms “a”, “an”, and “the” include plural references unless thecontext clearly dictates otherwise. It is further noted that the claimsmay be drafted to exclude any optional element. As such, this statementis intended to serve as antecedent basis for use of such exclusiveterminology as “solely,” “only” and the like in connection with therecitation of claim elements, or use of a “negative” limitation.

As will be apparent to those of skill in the art upon reading thisdisclosure, each of the individual embodiments described and illustratedherein has discrete components and features which may be readilyseparated from or combined with the features of any of the other severalembodiments without departing from the scope or spirit of the invention.Any recited method can be carried out in the order of events recited orin any other order, which is logically possible.

I. Methods and Systems

There are provided methods and systems to utilize the lime to form theprecipitation material that has certain polymorphs of calcium carbonate,such as the vaterite, which have useful properties as a component ofcertain building materials. The vaterite formed in the methods andsystems provided herein, can be a stable vaterite or a reactivevaterite. The reactive vaterite upon dissolution and re-precipitationwith water forms aragonite which has cementitious properties.Vaterite-containing precipitate provided herein can be used to replaceOrdinary Portland Cement (OPC) either entirely in applications such asbut not limited to, cement fiber board or partially as a supplementarycementitious material (SCM). The “lime” as used herein relates tocalcium oxide and/or calcium hydroxide. The presence and amount of thecalcium oxide and/or the calcium hydroxide in the lime would varydepending on the conditions for the lime formation.

The methods and systems provided herein have several advantages, such asbut not limited to, reduction of carbon dioxide emissions through theincorporation of the carbon dioxide back into the process to form theprecipitate comprising calcium carbonate. Production of the vateritecontaining precipitate, in the methods and systems provided herein,offers advantages including, operating expense savings through thereduction in fuel consumption, and reductions in carbon footprint.

Cement is a significant contributor to global carbon dioxide emissionswith over 1.5 billion metric tons emitted per year, corresponding toabout 5% of total emissions. Over 50% of the cement emissions may resultfrom the release of carbon dioxide from the decomposition of the limefeedstock (CaCO₃→CaO+CO₂). In the methods and systems provided herein,the emissions of the CO₂ from the calcination of the limestone to thelime may be avoided by recapturing it back in the cementitious vateritematerial. By recapturing the carbon dioxide, the vaterite product hasthe potential to eliminate significant amount of the cement carbondioxide emissions and total global emissions from all sources.

Accordingly, in one aspect, there are provided methods to form calciumcarbonate comprising vaterite, comprising dissolving lime in an aqueousbase solution under one or more precipitation conditions to produce aprecipitation material comprising calcium carbonate and a supernatantsolution, wherein the calcium carbonate comprises vaterite.

In one aspect, there are provided methods to form calcium carbonatecomprising vaterite, comprising (i) dissolving lime in an aqueous basesolution under one or more dissolution conditions to produce a firstaqueous solution comprising calcium salt; and (ii) treating the firstaqueous solution comprising calcium salt with a gaseous streamcomprising carbon dioxide under one or more precipitation conditions toform a precipitation material comprising calcium carbonate and asupernatant solution, wherein the calcium carbonate comprises vaterite.In some embodiments of the aforementioned aspects, the gaseous streamcomprising carbon dioxide is obtained from the calcination of thelimestone to form the lime.

Some aspects and embodiments of the methods and systems provided hereinare as illustrated in FIGS. 1-7 . It is to be understood that the stepsillustrated in FIGS. 1-7 may be modified or the order of the steps maybe changed or more steps may be added or deleted depending on thedesired outcome. As illustrated in FIGS. 1-7 , the lime is subjected tomethods and systems provided herein to produce the precipitationmaterial comprising calcium carbonate, wherein the calcium carbonatecomprises vaterite.

Calcination or calcining is a thermal treatment process to bring about athermal decomposition of the limestone. The “limestone” as used herein,means CaCO₃ and may further include other impurities typically presentin the limestone. Limestone is a naturally occurring mineral. Thechemical composition of this mineral may vary from region to region aswell as between different deposits in the same region. Therefore, thelime containing the calcium oxide and/or the calcium hydroxide obtainedfrom calcining limestone from each natural deposit may be different.Typically limestone may be composed of calcium carbonate (CaCO₃),magnesium carbonate (MgCO₃), silica (SiO₂), alumina (Al₂O₃), iron (Fe),sulphur (S) or other trace elements.

Limestone deposits are widely distributed. The limestone from thevarious deposits may differ in physical chemical properties and can beclassified according to their chemical composition, texture andgeological formation. Limestone may be classified into the followingtypes: high calcium where the carbonate content may be composed mainlyof calcium carbonate with a magnesium carbonate content not more than5%; magnesium containing magnesium carbonate to about 5-20%; ordolomitic which may contain between 20-45% of MgCO₃, the balance amountis calcium carbonate. Limestones from different sources may differconsiderably in chemical compositions and physical structures. It is tobe understood that the methods and systems provided herein apply to allthe cement plants calcining the limestone from any of the sources listedabove or commercially available. The quarries include, but not limitedto, quarries associated with cement kilns, quarries for lime rock foraggregate for use in concrete, quarries for lime rock for other purposes(road base), and/or quarries associated with lime kilns.

The limestone calcination is a decomposition process where the chemicalreaction for decomposition of the limestone is:CaCO₃→CaO+CO₂(g)

This step is illustrated in FIGS. 1-3 as a first step of the calcinationof the limestone to form the lime. The lime may be in dry form i.e.calcium oxide, and/or in wet form e.g. calcium hydroxide, depending onthe conditions. The production of the lime may depend upon the type ofkiln, conditions of the calcination, and the nature of the raw materiali.e. limestone. At relatively low calcination temperatures, productsformed in the kiln may contain both un-burnt carbonate and lime and maybe called underburnt lime. As the temperature increases, soft burnt orhigh reactive lime may be produced. At still higher temperatures, deadburnt or low reactive lime may be produced. Soft burnt lime is producedwhen the reaction front reaches the core of the charged limestone andconverts all carbonate present to lime. A high productive product may berelatively soft, contains small lime crystallites and has open porousstructure with an easily assessable interior. Such lime may have theoptimum properties of high reactivity, high surface area and low bulkdensity. Increasing the degree of calcination beyond this stage may makelime crystallites to grow larger, agglomerate and sinter. This mayresult in a decrease in surface area, porosity and reactivity and anincrease in bulk density. This product may be known as dead burnt or lowreactive lime. Without being limited by any theory, the methods andsystems provided herein utilize any one or the combination of theaforementioned lime. Therefore, in some embodiments, the lime is deadburnt, soft burnt, underburnt, or combinations thereof.

Production of the lime by calcining the limestone may be carried outusing various types of kilns, such as, but not limited to, a shaft kilnor a rotary kiln or an electric kiln. The use of the electric kiln inthe calcination and the advantages associated with it, have beendescribed in U.S. Provisional Application No. 63/046,239, filed Jun. 30,2020, which is fully incorporated herein by reference in its entirety.

These apparatuses for the calcining are suitable for calcining thelimestone in the form of lumps having diameters of several to tensmillimeters. Cement plant waste streams include waste streams from bothwet process and dry process plants, which plants may employ shaft kilns,rotary kilns, electric kilns, or combinations thereof and may includepre-calciners. These industrial plants may each burn a single fuel, ormay burn two or more fuels sequentially or simultaneously.

As illustrated in FIGS. 1-3 , the limestone obtained from the limestonequarry is subjected to the calcination in a cement plant resulting inthe formation of the lime and CO₂ gas. The lime may be calcium oxide inthe form of a solid from dry kilns/cement processes and/or may be acombination of calcium oxide and calcium hydroxide in the form of slurryin wet kilns/cement processes. When wet the calcium oxide (also known asa base anhydride that converts to its hydroxide form in water) may bepresent in its hydrated form such as but not limited to, calciumhydroxide. While calcium hydroxide (also called slaked lime) is a commonhydrated form of calcium oxide, other intermediate hydrated and/or watercomplexes may also be present in the slurry, and are all included withinthe scope of the methods and systems provided herein. It is to beunderstood that while the lime is illustrated as CaO in some of thefigures herein, it may be present as Ca(OH)₂ or combination of CaO andCa(OH)₂.

The lime may be sparingly soluble in water. In the methods and systemsprovided herein, the lime solubility is increased by its treatment withsolubilizers.

In the methods and systems provided herein, the lime is solvated ordissolved or solubilized with a solubilizer, such as an aqueous basesolution (step A in FIGS. 1-3 ) under one or more dissolution conditionsto produce a first aqueous solution comprising calcium salt. Forillustration purposes only, the aqueous base solution, e.g. N-containinginorganic salt solution is being illustrated in the figures as ammoniumchloride (NH₄Cl) solution and the subsequent calcium salt is bringillustrated as calcium chloride (CaCl₂). Various examples of the baseshave been provided herein and are all within the scope of the invention.

The “base” as used herein includes any base or conjugate base of anacid. In some embodiments, the base is a solubilizing base thatsolubilizes or dissolves the calcium from the lime and leaves the solidimpurities. The bases include without limitation, N-containing inorganicsalt, N-containing organic salt, or combination thereof.

The “N-containing inorganic salt” as used herein includes any inorganicsalt with nitrogen in it. Examples of N-containing inorganic saltinclude, but not limited to, ammonium halide (halide is any halogen),ammonium sulfate, ammonium sulfite, ammonium nitrate, ammonium nitrite,and the like. In some embodiments, the ammonium halide is ammoniumchloride or ammonium bromide. In some embodiments, the ammonium halideis ammonium chloride.

The “N-containing organic salt” as used herein includes any salt of anorganic compound with nitrogen in it. Examples of N-containing organiccompounds include, but not limited to, aliphatic amine, alicyclic amine,heterocyclic amine, and combinations thereof.

The “aliphatic amine” as used herein includes any alkyl amine of formula(R)_(n)—NH_(3-n) where n is an integer from 1-3, wherein R isindependently between C1-C8 linear or branched and substituted orunsubstituted alkyl. An example of the corresponding halide salt(chloride salt, bromide salt, fluoride salt, or iodide salt) of thealkyl amine of formula (R)_(n)—NH_(3-n) is (R)_(n)—NH_(4-n) ⁺Cl⁻. Insome embodiments, when R is substituted alkyl, the substituted alkyl isindependently substituted with halogen, hydroxyl, acid and/or ester.

For example, when R is alkyl in (R)_(n)—NH_(3-n), the alkyl amine can bea primary alkyl amine, such as for example only, methylamine,ethylamine, butylamine, pentylamine, etc.; the alkyl amine can be asecondary amine, such as for example only, dimethylamine, diethylamine,methylethylamine, etc.; and/or the alkyl amine can be a tertiary amine,such as for example only, trimethylamine, triethylamine, etc.

For example, when R is substituted alkyl substituted with hydroxyl in(R)_(n)—NH_(3-n), the substituted alkyl amine is an alkanolamineincluding, but not limited to, monoalkanolamine, dialkanolamine, ortrialkanolamine, such as e.g. monoethanolamine, diethanolamine, ortriethanolamine, etc.

For example, when R is substituted alkyl substituted with halogen in(R)_(n)—NH_(3-n), the substituted alkyl amine is, for example,chloromethylamine, bromomethylamine, chloroethylamine, bromoethylamine,etc.

For example, when R is substituted alkyl substituted with acid in(R)_(n)—NH_(3-n), the substituted alkyl amine is, for example, aminoacids. In some embodiments, the aforementioned amino acid has a polaruncharged alkyl chain, examples include without limitation, serine,threonine, asparagine, glutamine, or combinations thereof. In someembodiments, the aforementioned amino acid has a charged alkyl chain,examples include without limitation, arginine, histidine, lysine,aspartic acid, glutamic acid, or combinations thereof. In someembodiments, the aforementioned amino acid is glycine, proline, orcombination thereof.

The “alicyclic amine” as used herein includes any alicyclic amine offormula (R)_(n)—NH_(3-n) where n is an integer from 1-3, wherein R isindependently one or more all-carbon rings which may be either saturatedor unsaturated, but do not have aromatic character. Alicyclic compoundsmay have one or more aliphatic side chains attached. An example of thecorresponding salt of the alicyclic amine of formula (R)_(n)—NH_(3-n) is(R)_(n)—NH_(4-n) ⁺Cl⁻. Examples of alicyclic amine include, withoutlimitation, cycloalkylamine:cyclopropylamine, cyclobutylamine,cyclopentylamine, cyclohexylamine, cycloheptylamine, cyclooctylamine,and so on.

The “heterocyclic amine” as used herein includes at least oneheterocyclic aromatic ring attached to at least one amine. Examples ofheterocyclic rings include, without limitation, pyrrole, pyrrolidine,pyridine, pyrimidine, etc. Such chemicals are well known in the art andare commercially available.

In the methods and systems provided herein, the lime is dissolved orsolubilized with the solubilizer, such as the aqueous base solution(step A in FIGS. 1-3 ) under one or more dissolution conditions toproduce the first aqueous solution comprising calcium salt, and agaseous stream comprising ammonia.

As illustrated in step A of FIGS. 1-3 , the base is exemplified asammonium chloride (NH₄Cl). The lime is solubilized by treatment withNH₄Cl (new and recycled as further explained below) when the reactionthat may occur is:CaO+2NH₄Cl(aq)→CaCl₂(aq)+2NH₃+H₂OCa(OH)₂+2NH₄Cl(aq)→2NH₃+CaCl₂+2H₂O

Similarly, when the base is N-containing organic salt, the reaction maybe shown as below:CaO+2NH₃RCl→CaCl₂(aq)+2NH₂R+H₂O

In some embodiments, the base or the N-containing inorganic salt suchas, but not limited to, an ammonium salt, e.g. ammonium chloridesolution may be supplemented with anhydrous ammonia or an aqueoussolution of ammonia to maintain an optimum level of ammonium chloride inthe solution.

In some embodiments, the first aqueous solution comprising calcium saltobtained after dissolution of the lime may contain sulfur depending onthe source of the lime. The sulfur may get introduced into the firstaqueous solution after the solubilization of the lime with any of thebases described herein. In an alkaline solution, various sulfurcompounds containing various sulfur ionic species may be present in thesolution including, but not limited to, sulfite (SO₃ ²⁻), sulfate (SO₄²⁻), hydrosulfide (HS⁻), thiosulfate (S₂O₃ ²⁻), polysulfides (S_(n) ²⁻),thiol (RSH), and the like. The “sulfur compound” as used herein,includes any sulfur ion containing compound.

In some embodiments, the first aqueous solution further comprises thebase, such as, ammonia and/or N-containing inorganic or N-containingorganic salt.

In some embodiments, the amount of the base such as, the N-containinginorganic salt, the N-containing organic salt, or combinations thereof,is in more than 20% excess or more than 30% excess to the lime. In someembodiments, the molar ratio of the base:lime (or N-containing inorganicsalt:lime or N-containing organic salt:lime or ammonium chloride:lime)is between 0.5:1-2:1; or 0.5:1-1.5:1; or 1:1-1.5:1; or 1.5:1; or 2:1; or2.5:1; or 1:1.

In some embodiments of the methods described herein, no polyhydroxycompounds are used to form the precipitation material and/or theproducts provided herein.

In some embodiments of the methods and systems described herein, one ormore dissolution conditions are selected from the group consisting oftemperature between about 30-200° C., or between about 30-150° C., orbetween about 30-100° C., or between about 30-75° C., or between about30-50° C., or between about 40-200° C., or between about 40-150° C., orbetween about 40-100° C., or between about 40-75° C., or between about40-50° C., or between about 50-200° C., or between about 50-150° C., orbetween about 50-100° C.; pressure between about 0.1-50 atm, or betweenabout 0.1-40 atm, or between about 0.1-30 atm, or between about 0.1-20atm, or between about 0.1-10 atm, or between about 0.5-20 atm;N-containing inorganic or organic salt wt % in water between about0.5-50%, or between about 0.5-25%, or between about 0.5-10%, or betweenabout 3-30%, or between about 5-20%; or combinations thereof.

Agitation may be used to affect dissolution of the lime with the aqueousbase solution in the dissolution reactor, for example, by eliminatinghot and cold spots. In some embodiments, the concentration of the limein water may be between 1 and 10 g/L, 10 and 20 g/L, 20 and 30 g/L, 30and 40 g/L, 40 and 80 g/L, 80 and 160 g/L, 160 and 320 g/L, 320 and 640g/L, or 640 and 1280 g/L. To optimize the dissolution/solvation of thelime, high shear mixing, wet milling, and/or sonication may be used tobreak open the lime. During or after high shear mixing and/or wetmilling, the lime suspension may be treated with the base.

In some embodiments, the dissolution of the lime with the base(illustrated as e.g. ammonium chloride) results in the formation of thefirst aqueous solution comprising calcium salt and solids. In someembodiments, the solid insoluble impurities may be removed from thefirst aqueous solution of the calcium salt (step B in FIGS. 1-3 ) beforethe aqueous solution is treated with the carbon dioxide in the process.The solids may optionally be removed from the aqueous solution byfiltration and/or centrifugation techniques.

It is to be understood that the step B in FIGS. 1-3 is optional and insome embodiments, the solids may not be removed from the aqueoussolution (not shown in FIGS. 1-3 ) and the aqueous solution containingcalcium salts as well as the solids are contacted with the carbondioxide (in step C in FIGS. 1-3 ) to form the precipitates. In suchembodiments, the precipitation material further comprises solids.

In some embodiments, the solids obtained from the dissolution of thelime (shown as insoluble impurities in FIGS. 1-3 ) are calcium depletedsolids and may be used as a cement substitute (such as a substitute forPortland cement). In some embodiments, the solids comprise silicates,iron oxides, alumina, or combinations thereof. The silicates include,without limitation, clay (phyllosilicate), alumino-silicate, etc.

In some embodiments, the solids are between 1-40 wt %; or between 1-30wt %; or between 1-20 wt %; or between 1-10 wt % or between 1-5 wt %; orbetween 1-2 wt %, in the aqueous solution, in the precipitationmaterial, or combinations thereof.

As illustrated in step C in FIG. 1 , the first aqueous solutioncomprising calcium salt (and optionally solids) and dissolved ammoniaand/or ammonium salt is contacted under one or more precipitationconditions with the gaseous stream comprising carbon dioxide recycledfrom the calcination step of the respective process, to form aprecipitation material comprising calcium carbonate and a supernatantsolution, wherein the calcium carbonate comprises vaterite, shown in thereaction below:CaCl₂(aq)+2NH₃(aq)+CO₂(g)+H₂O→CaCO₃(s)+2NH₄Cl(aq)

The absorption of the CO₂ into the first aqueous solution producesCO₂-charged water containing carbonic acid, a species in equilibriumwith both bicarbonate and carbonate. The precipitation material isprepared under one or more precipitation conditions (as describedherein) suitable to form vaterite containing or PCC material.

In one aspect, there are provided methods to form calcium carbonatecomprising vaterite, comprising (i) calcining limestone to form lime anda gaseous stream comprising carbon dioxide; (ii) dissolving the lime inan aqueous base solution under one or more dissolution conditions toproduce a first aqueous solution comprising calcium salt, and a gaseousstream comprising ammonia; and (iii) treating the first aqueous solutioncomprising calcium salt with the gaseous stream comprising carbondioxide and the gaseous stream comprising ammonia under one or moreprecipitation conditions to form a precipitation material comprisingcalcium carbonate and a supernatant solution, wherein the calciumcarbonate comprises vaterite. This aspect is illustrated in FIG. 2 ,wherein the gaseous stream comprising CO₂ from the calcination step andthe gaseous stream comprising NH₃ from step A of the process isrecirculated to the precipitation reactor (step C) for the formation ofthe precipitation material. Remaining steps of FIG. 2 are identical tothe steps of FIG. 1 . It is to be understood that the processes of bothFIG. 1 and FIG. 2 can also take place simultaneously such that the base,such as the N-containing inorganic salt or the N-containing organic saltand optionally ammonia may be partially present in the first aqueoussolution and partially present in the gaseous stream.

The reaction taking place in the aforementioned aspect may be shown asbelow:CaCl₂(aq)+2NH₃(g)+CO₂(g)+H₂O→CaCO₃(s)+2NH₄Cl(aq)

In some embodiments of the aspects and embodiments provided herein, thegaseous stream comprising ammonia may have ammonia from an externalsource and/or is recovered and recirculated from step A of the process.

In some embodiments of the aspects and embodiments provided herein,wherein the gaseous stream comprises ammonia and/or the gaseous streamcomprises carbon dioxide, no external source of carbon dioxide and/orammonia is used and the process is a closed loop process. Such closedloop process is being illustrated in the figures described herein.

In some embodiments, the dissolution of the lime with some of theN-containing organic salt may not result in the formation of ammonia gasor the amount of ammonia gas formed may not be substantial. Inembodiments where the ammonia gas is not formed or is not formed insubstantial amounts, the methods and systems illustrated in FIG. 1 wherethe first aqueous solution comprising calcium salt is treated with thecarbon dioxide gas, are applicable. In such embodiments, the organicamine salt may remain in the aqueous solution in fully or partiallydissolved state or may separate as an organic amine layer, as shown inthe reaction below:CaO+2NH₃R⁺Cl⁻→CaCl₂(aq)+2NH₂R+H₂O

The N-containing organic salt or the N-containing organic compoundremaining in the supernatant solution after the precipitation may becalled residual N-containing organic salt or residual N-containingorganic compound. Methods and systems have been described herein torecover the residual compounds from the precipitate as well as thesupernatant solution.

In one aspect, there are provided methods to form calcium carbonatecomprising vaterite, comprising (i) calcining limestone to form lime anda gaseous stream comprising carbon dioxide; (ii) dissolving the lime inan aqueous N-containing inorganic salt solution or N-containing organicsalt solution under one or more dissolution conditions to produce afirst aqueous solution comprising calcium salt, and a gaseous streamcomprising ammonia; (iii) recovering the gaseous stream comprisingcarbon dioxide and the gaseous stream comprising ammonia and subjectingthe gaseous streams to a cooling process under one or more coolingconditions to condense a second aqueous solution comprising ammoniumbicarbonate, ammonium carbonate, ammonia, or combinations thereof; and(iv) treating the first aqueous solution comprising calcium salt withthe second aqueous solution comprising ammonium bicarbonate, ammoniumcarbonate, ammonia, or combinations thereof under one or moreprecipitation conditions to form a precipitation material comprisingcalcium carbonate and a supernatant solution, wherein the calciumcarbonate comprises vaterite. This aspect is illustrated in FIG. 3 ,wherein the gaseous stream comprising CO₂ from the calcination step andthe gaseous stream comprising NH₃ from step A of the process isrecirculated to the cooling reactor/reaction (step F) for the formationof the carbonate and bicarbonate solutions as shown in the reactionsfurther herein below. Remaining steps of FIG. 3 are identical to thesteps of FIGS. 1 and 2 .

It is to be understood that the aforementioned aspect illustrated inFIG. 3 may be combined with the aspects illustrated in FIG. 1 and/orFIG. 2 such that the precipitation step C comprises treating the firstaqueous solution comprising calcium salt with the second aqueoussolution comprising ammonium bicarbonate, ammonium carbonate, ammonia,or combinations thereof (illustrated in FIG. 3 ), as well as comprisestreating the first aqueous solution comprising calcium salt with thegaseous stream comprising carbon dioxide (illustrated in FIG. 1 ) and/orcomprises treating the first aqueous solution comprising calcium saltwith the gaseous stream comprising carbon dioxide and the gaseous streamcomprising ammonia (illustrated in FIG. 2 ). In such embodiments, thegaseous stream comprising carbon dioxide is split between the streamgoing to the cooling process and the stream going to the precipitationprocess. Similarly, in such embodiments, the gaseous stream comprisingammonia is split between the stream going to the cooling process and thestream going to the precipitation process. Any combination of theprocesses depicted in FIGS. 1-3 is possible and all are within the scopeof this disclosure.

In some embodiments of the aforementioned aspects, the second aqueoussolution further comprises ammonium carbamate. Ammonium carbamate has aformula NH₄[H₂NCO₂] consisting of ammonium ions NH₄ ⁺, and carbamateions H₂NCO₂ ⁻. In some embodiments of the aforementioned aspect andembodiments, the second aqueous solution comprises ammonium bicarbonate,ammonium carbonate, ammonia, ammonium carbamate, or combinationsthereof.

The combination of these condensed products in the second aqueoussolution may be dependent on the one or more of the cooling conditions.Table 1 presented below represents various combinations of the condensedproducts in the second aqueous solution.

TABLE 1 Ammonium Ammonium Ammonium carbonate bicarbonate Ammoniacarbamate X X X X X X X X X X X X X X X X X X X X X X X X X X X X X

In some embodiments of the aforementioned aspect and embodiments, thegaseous stream (e.g. the gaseous streams going to the coolingreaction/reactor (step F in FIGS. 1-3 )) further comprises water vapor.In some embodiments of the aforementioned aspect and embodiments, thegaseous stream further comprises between about 20-90%; or between about20-80%; or between about 20-70%; or between about 20-60%; or betweenabout 20-55%; or between about 20-50%; or between about 20-40%; orbetween about 20-30%; or between about 20-25%; or between about 30-90%;or between about 30-80%; or between about 30-70%; or between about30-60%; or between about 30-50%; or between about 30-40%; or betweenabout 40-90%; or between about 40-80%; or between about 40-70%; orbetween about 40-60%; or between about 40-50%; or between about 50-90%;or between about 50-80%; or between about 50-70%; or between about50-60%; or between about 60-90%; or between about 60-80%; or betweenabout 60-70%; or between about 70-90%; or between about 70-80%; orbetween about 80-90%, water vapor.

In some embodiments of the aforementioned aspect and embodiments, noexternal water is added to the cooling process. It is to be understoodthat the cooling process is similar to condensation of the gases (butnot similar to the absorption of the gases) in the existing water vaporssuch that the gases are not absorbed in the water but are as such cooleddown together with the water vapors. Condensation of the gases into aliquid stream may provide process control advantages compared toabsorbing the vapors. For example only, condensation of the gases intothe liquid stream may allow pumping of the liquid stream into theprecipitation step. Pumping of the liquid stream may be lower in costthan compression of a vapor stream into the absorption process.

Intermediate steps in the cooling reaction/reactor may include theformation of ammonium carbonate and/or ammonium bicarbonate and/orammonium carbamate, by reactions as below:2NH₃+CO₂+H₂O→(NH₄)₂CO₃NH₃+CO₂+H₂O→(NH₄)HCO₃2NH₃+CO₂→(NH₄)NH₂CO₂

Similar reactions may be shown for the N-containing organic salt:2NH₂R+CO₂+H₂O→(NH₃R)₂CO₃NH₂R+CO₂+H₂O→(NH₃R)HCO₃

An advantage of cooling the ammonia in the cooling reaction/reactor isthat ammonia may have a limited vapor pressure in the vapor phase of thedissolution reaction. By reacting the ammonia with CO₂, as shown in thereactions above, can remove some ammonia from the vapor space, allowingmore ammonia to leave the dissolution solution.

The second aqueous solution comprising ammonium bicarbonate, ammoniumcarbonate, ammonia, (and optionally ammonium carbamate) or combinationsthereof (exiting the cooling reaction/reactor in FIG. 3 ) is thentreated with the first aqueous solution comprising calcium salt from thedissolution reaction/reactor, in the precipitation reaction/reactor(step C) to form the precipitation material comprising vaterite:(NH₄)₂CO₃+CaCl₂→CaCO₃(vaterite)+2NH₄Cl(NH₄)HCO₃+NH₃+CaCl₂→CaCO₃(vaterite)+2NH₄Cl+H₂O2(NH₄)HCO₃+CaCl₂→CaCO₃(vaterite)+2NH₄Cl+H₂O+CO₂(NH₄)NH₂CO₂+H₂O+CaCl₂→CaCO₃(vaterite)+2NH₄Cl

Independent of any intermediate steps, the combination of the reactionslead to an overall process chemistry of:CaO(lime)→CaCO₃(vaterite)

In some embodiments of the aspects and embodiments provided herein, theone or more cooling conditions comprise temperature between about 0-200°C., or between about 0-150° C., or between about 0-75° C., or betweenabout 0-100° C., or between about 0-80° C., or between about 0-60° C.,or between about 0-50° C., or between about 0-40° C., or between about0-30° C., or between about 0-20° C., or between about 0-10° C., orbetween about 10-100° C., or between about 10-80° C., or between about10-60° C., or between about 10-50° C., or between about 10-40° C., orbetween about 10-30° C., or between about 20-100° C., or between about20-80° C., or between about 20-60° C., or between about 20-50° C., orbetween about 20-40° C., or between about 20-30° C., or between about30-100° C., or between about 30-80° C., or between about 30-60° C., orbetween about 30-50° C., or between about 30-40° C., or between about40-100° C., or between about 40-80° C., or between about 40-60° C., orbetween about 50-100° C., or between about 50-80° C., or between about60-100° C., or between about 60-80° C., or between about 70-100° C., orbetween about 70-80° C.

In some embodiments of the aspects and embodiments provided herein, theone or more cooling conditions comprise pressure between about 0.5-50atm; or between about 0.5-25 atm; or between about 0.5-10 atm; orbetween about 0.1-10 atm; or between about 0.5-1.5 atm; or between about0.3-3 atm.

In some embodiments, the formation and the quality of the reactivevaterite formed in the methods and systems provided herein, is dependenton the amount and/or the ratio of the condensed products in the secondaqueous solution comprising ammonium bicarbonate, ammonium carbonate,ammonia, ammonium carbamate, or combinations thereof.

In some embodiments, the presence or absence or distribution of thecondensed products in the second aqueous solution comprising ammoniumbicarbonate, ammonium carbonate, ammonia, ammonium carbamate, orcombinations thereof, can be optimized in order to maximize theformation of the reactive vaterite and/or to obtain a desired particlesize distribution. This optimization can be based on the one or morecooling conditions, such as, pH of the aqueous solution in the coolingreactor, flow rate of the CO₂ and the NH₃ gases, and/or ratio of theCO₂:NH₃ gases. The inlets for the cooling reactor (F in FIG. 3 ) may becarbon dioxide (CO_(2(g))), the dissolution reactor gas exhaustcontaining ammonia (NH_(3(g))), water vapor, and optionally fresh makeupwater (or some other dilute water stream). The outlet may be aslipstream of the reactor's recirculating fluid (the second aqueoussolution), which is directed to the precipitation reactor for contactingwith the first aqueous solution and optionally additional carbon dioxideand/or ammonia. The pH of the system may be controlled by regulating theflow rate of CO₂ and NH₃ into the cooling reactor. The conductivity ofthe system may be controlled by addition of dilute makeup water to thecooling reactor. Volume may be maintained constant by using a leveldetector in the cooling reactor or it's reservoir.

In some embodiments, higher pH of the aqueous solution in the coolingreactor (may be achieved by higher flow rate of ammonia) may favorcarbamate formation whereas lower pH of the aqueous solution in thecooling reactor (may be achieved by lower flow rate of ammonia) mayfavor carbonate and/or bicarbonate formation. In some embodiments, theone or more cooling conditions include pH of the aqueous solution formedin the cooling reactor to be between about 8-12, or between about 8-11,or between about 8-10, or between about 8-9.

In some embodiments, the flow rate of the carbon dioxide can be modifiedto achieve a desired pH of the second aqueous solution exiting thecooling reactor. For example, if the pH of the second aqueous solutionis high, the flow rate of the carbon dioxide can be increased to reducethe pH or if the pH of the second aqueous solution is low, the flow rateof the carbon dioxide can be reduced to increase the pH. The effect ofthe flow rate of the CO₂ on the pH of the second aqueous solution and onthe ratio of the carbamate:carbonate:bicarbonate formation can be seenin Example 3 provided herein. Similarly, the effect of the ratio ofCO₂:NH₃ on the pH of the second aqueous solution and on the ratio of thecarbamate:carbonate:bicarbonate formation can be seen in Example 4provided herein. In some embodiments, the one or more cooling conditionsinclude ratio of CO₂:NH₃ in the cooling reactor to be between about0.1:1-20:1, or between about 0.1:1-1:1, or between about 0.1:1-2:1, orbetween about 5:1-10:1, or between about 1:1-5:1, or between about2:1-5:1.

It is to be understood that while FIG. 3 illustrates a separate coolingreaction/reactor, in some embodiments, the dissolution reaction/reactormay be integrated with the cooling reaction/reactor, as illustrated inFIGS. 4-7 . For example, the dissolution reactor may be integrated witha condenser acting as a cooling reactor. Both the lime and the aqueousbase solution (illustrated as NH₄Cl in FIGS. 4-7 ) are fed to thedissolution reaction/reactor, when the first aqueous solution comprisingcalcium salt (illustrated as CaCl₂) is formed. The solution mayoptionally contain solid impurities that stay at the bottom of thedissolution reactor. The first aqueous solution comprising calcium salt(illustrated as CaCl₂) is withdrawn from the dissolutionreaction/reactor to be processed further for precipitation. The gaseousstream comprising ammonia and water vapor passes to the upper section ofthe dissolution reactor (i.e. the cooling reactor; illustrated in FIGS.4-7 ) where it is cooled along with the carbon dioxide to condense intothe second aqueous solution. The carbon dioxide may be obtained from aplant where limestone is being calcined into the lime and the carbondioxide. The carbon dioxide is then fed to the vapor phase of thecooling reactor. The second aqueous solution comprising ammoniumbicarbonate, ammonium carbonate, ammonia, ammonium carbamate, orcombinations thereof, is collected from the cooling reactor usingvarious means, such as, e.g. one or more trays (e.g. as illustrated inFIG. 4 ).

In one aspect, there is provided an integrated reactor comprising:

a dissolution reactor integrated with a cooling reactor wherein thedissolution reactor is positioned below the cooling reactor;

the dissolution reactor is configured to dissolve lime in an aqueousN-containing inorganic salt solution or N-containing organic saltsolution under one or more dissolution conditions to produce a firstaqueous solution comprising calcium salt, and a gaseous streamcomprising ammonia and water vapor; and

the cooling reactor operably connected to the dissolution reactor andconfigured to receive and condense under one or more cooling conditionsthe gaseous stream comprising ammonia and water vapor from thedissolution reactor and a gaseous stream comprising carbon dioxide fromcalcination of limestone to the lime; and form a second aqueous solutioncomprising ammonium bicarbonate, ammonium carbonate, ammonia, ammoniumcarbamate, or combinations thereof.

Various other configurations of the integrated reactor described above,are as illustrated in FIGS. 5-7 . FIG. 5 is another illustration of FIG.4 . FIG. 6 further illustrates CO₂ introduction into the vapor space ofthe cooling reactor that is packed with a packing material. The packingmaterial can be any inert material used to aid mass transfer of NH₃ andCO₂ from the vapor into the liquid phase. The packing can be randompacking or structured packing. The random packing material can be anymaterial that has individual pieces packed into the vessel or thereactor. The structured packing material can be any material that has anindividual monolith that is shaped to provide surface area and enhancemass transfer. Examples of loose or unstructured or random packingmaterial include, but not limited to, Raschig rings (such as in ceramicmaterial), pall rings (e.g. in metal and plastic), lessing rings,Michael Bialecki rings (e.g. in metal), berl saddles, intalox saddles(e.g. in ceramic), super intalox saddles, Tellerette® ring (e.g. spiralshape in polymeric material), etc.

Examples of structured packing material include, but not limited to,thin corrugated metal plates or gauzes (honeycomb structures) indifferent shapes with a specific surface area. The structured packingmaterial may be used as a ring or a layer or a stack of rings or layersthat have diameter that may fit into the diameter of the reactor. Thering may be an individual ring or a stack of rings fully filling thereactor. In some embodiments, the voids left out by the structuredpacking in the reactor are filled with the unstructured or randompacking material.

Examples of structured packing material includes, without limitation,Flexipac®, Intalox®, Flexipac® HC®, etc. In a structured packingmaterial, corrugated sheets may be arranged in a crisscross pattern tocreate flow channels for the vapor phase. The intersections of thecorrugated sheets may create mixing points for the liquid and vaporphases. The structured packing material may be rotated about the column(reactor) axis to provide cross mixing and spreading of the vapor andliquid streams in all directions. The structured packing material may beused in various corrugation sizes and the packing configuration may beoptimized to attain the highest efficiency, capacity, and pressure droprequirements of the reactor. The structured packing material may be madeof a material of construction including, but not limited to, titanium,stainless steel alloys, carbon steel, aluminum, nickel alloys, copperalloys, zirconium, thermoplastic, etc. The corrugation crimp in thestructured packing material may be of any size, including, but notlimited to, Y designated packing having an inclination angle of 45° fromthe horizontal or X designated packing having an inclination angle of60° from the horizontal. The X packing may provide a lower pressure dropper theoretical stage for the same surface area. The specific surfacearea of the structured packing may be between 50-800 m²/m³; or between75-350 m²/m³; or between 200-800 m²/m³; or between 150-800 m²/m³; orbetween 500-800 m²/m³.

In some embodiments, the cooling reactor further comprises an inlet tointroduce a scrubbing fluid, such as e.g. ammonium chloride solution(FIG. 6 ) or water (FIG. 7 ) to the top of the packing material of thecooling reactor. The scrubbing fluids such as ammonium chloridesolution, or ammonia solution, or water or the like, facilitateformation of the condensed products such as ammonium bicarbonate,ammonium carbonate, ammonia, ammonium carbamate, or combinationsthereof. The scrubbing fluid can provide more liquid volume for thecondensation of the gases. In some embodiments, if the scrubbing fluidis pre-cooled, then it can further aid the condensation process. Whenthe scrubbing fluid is the ammonium chloride solution (FIG. 6 ), theammonium chloride solution can be a portion of the ammonium chloridesolution being fed to the dissolution reactor. In some embodiments, thesecond aqueous solution comprising ammonium bicarbonate, ammoniumcarbonate, ammonia, ammonium carbamate, ammonium chloride, orcombinations thereof, collected from the condensed liquid from thecooling reactor, may be recycled back to the cooling reactor as thescrubbing fluid to further facilitate the condensation process. In someembodiments, the second aqueous solution may be cooled in a heatexchanger prior to recycling it back to the cooling reactor.

Other gases such as flue gas in the gaseous stream comprising carbondioxide (obtained from the calcination process) may exit the coolingreactor (illustrated in FIGS. 4-7 ).

In the aforementioned aspects, both the dissolution and the coolingreactors are fitted with inlets and outlets to receive the requiredgases and collect the aqueous streams. In some embodiments of theaforementioned aspect, the dissolution reactor comprises a stirrer tomix the lime with the aqueous base solution. The stirrer can alsofacilitate upward movement of the gases. In some embodiments of theaforementioned aspect, the dissolution reactor is configured to collectthe solids settled at the bottom of the reactor after removing the firstaqueous solution comprising calcium salt. In some embodiments of theaforementioned aspect, the cooling tower comprises one or more traysconfigured to catch and collect the condensed second aqueous solutionand prevent it from falling back into the dissolution reactor. As such,the cooling/condensation may be accomplished through use of infusers,bubblers, fluidic Venturi reactors, spargers, gas filters, sprays,trays, or packed column reactors, and the like.

In some embodiments, the cooling reactor comprises a heat exchanger inthe reactor or a heat exchanging surface. The heat exchanger maycomprise one or more tubes with a cold fluid circulating inside thetubes such that the cold fluid is isolated from the vapor phase in thecooling reactor but facilitates lowering the temperature of the coolingreactor for the condensation of the gases. The cold fluid can be coolingwater, the scrubbing solution described above, and the like. In someembodiments, the second aqueous solution exiting the cooling reactor iscooled down by the heat exchanger before it is used as the scrubbingsolution.

As illustrated in step C in FIGS. 1-2 , the first aqueous solutioncomprising calcium salt, from treatment of the lime with a base asdescribed herein, such as e.g. an ammonium salt or an ammonium halide,is contacted with CO₂ and optionally NH₃ from step A at any time before,during, or after the first aqueous solution comprising calcium salt issubjected to one or more precipitation conditions (i.e., conditionsallowing for precipitation of the precipitation material). Similarly, asillustrated in step C in FIG. 3 , the first aqueous solution comprisingcalcium salt, from treatment of the lime with a base as described hereinfor step A, such as e.g. an ammonium salt or an ammonium halide, iscontacted with the second aqueous solution comprising ammoniumbicarbonate, ammonium carbonate, ammonia, ammonium carbamate, orcombinations thereof from the cooling reaction/reactor at any timebefore, during, or after the first aqueous solution comprising calciumsalt is subjected to one or more precipitation conditions (i.e.,conditions allowing for precipitation of the precipitation material).

Accordingly, in some embodiments, the first aqueous solution comprisingcalcium salt is contacted with the CO₂ (and NH₃ as in FIG. 2 or secondaqueous solution as in FIG. 3 ) prior to subjecting the aqueous solutionto the one or more precipitation conditions that favor formation of theprecipitation material comprising stable or reactive vaterite or PCC. Insome embodiments, the first aqueous solution comprising calcium salt iscontacted with the CO₂ (and NH₃ as in FIG. 2 or second aqueous solutionas in FIG. 3 ) while the aqueous solution is being subjected to the oneor more precipitation conditions that favor formation of theprecipitation material comprising stable or reactive vaterite or PCC. Insome embodiments, the first aqueous solution comprising calcium salt iscontacted with the CO₂ (and NH₃ as in FIG. 2 or second aqueous solutionas in FIG. 3 ) prior to and while subjecting the aqueous solution to theone or more precipitation conditions that favor formation of theprecipitation material comprising stable or reactive vaterite or PCC. Insome embodiments, the first aqueous solution comprising calcium salt iscontacted with the CO₂ (and NH₃ as in FIG. 2 or second aqueous solutionas in FIG. 3 ) after subjecting the aqueous solution to the one or moreprecipitation conditions that favor formation of the precipitationmaterial comprising stable or reactive vaterite or PCC.

In some embodiments, the contacting of the first aqueous solutioncomprising calcium salt with carbon dioxide and optionally ammonia orsecond aqueous solution is achieved by contacting the first aqueoussolution to achieve and maintain a desired pH range, a desiredtemperature range, and/or desired divalent cation concentration using aconvenient protocol as described herein (precipitation conditions). Insome embodiments, the systems include a precipitation reactor configuredto contact the first aqueous solution comprising calcium salt withcarbon dioxide and optionally ammonia from step A of the process or thesystems include a precipitation reactor configured to contact the firstaqueous solution comprising calcium salt with the second aqueoussolution comprising ammonium bicarbonate, ammonium carbonate, ammonia,(optionally ammonium carbamate), or combinations thereof.

In some embodiments, the first aqueous solution comprising calcium saltmay be placed in a precipitation reactor, wherein the amount of thefirst aqueous solution comprising calcium salt added is sufficient toraise the pH to a desired level (e.g., a pH that induces precipitationof the precipitation material) such as pH 7-9, pH 7-8.7, pH 7-8.5, pH7-8, pH 7.5-8, pH 8-8.5, pH 8.5-9, pH 9-14, pH 10-14, pH 11-14, pH12-14, or pH 13-14. In some embodiments, the pH of the first aqueoussolution comprising calcium salt when contacted with the carbon dioxideand optionally the NH₃ or the second aqueous solution, is maintained atbetween 7-9 or between 7-8.7 or between 7-8.5 or between 7.5-8.5 orbetween 7-8, or between 7.6-8.5, or between 8-8.5, or between 7.5-9.5 inorder to form the precipitation material comprising stable vaterite,reactive vaterite or PCC.

In some embodiments, the first aqueous solution is immobilized in acolumn or bed (an example of a configuration of the precipitationreactor). In such embodiments, water is passed through or over an amountof the calcium salt solution sufficient to raise the pH of the water toa desired pH or to a particular divalent cation (Ca²⁺) concentration. Insome embodiments, the first aqueous solution may be cycled more thanonce, wherein a first cycle of precipitation removes primarily calciumcarbonate minerals and leaves an alkaline solution to which additionalfirst aqueous solution comprising calcium salt may be added. The gaseousstream comprising the carbon dioxide and optionally the NH₃, or thesecond aqueous solution when contacted with the recycled solution of theaqueous solution, allows for the precipitation of more calcium carbonateand/or bicarbonate compounds. It will be appreciated that, in theseembodiments, the aqueous solution following the first cycle ofprecipitation may be contacted with the gaseous stream comprising theCO₂ and optionally the NH₃ (or with the second aqueous solution) before,during, and/or after the first aqueous solution comprising calcium salthas been added. In these embodiments, the water may be recycled or newlyintroduced. As such, the order of addition of the gaseous streamcomprising the CO₂ and optionally the NH₃ and the first aqueous solutioncomprising calcium salt may vary. For example, the first aqueoussolution comprising calcium salt may be added to, for example, brine,seawater, or freshwater, followed by the addition of the gaseous streamcomprising the CO₂ and optionally the NH₃, or the second aqueoussolution. In another example, the gaseous stream comprising the CO₂ andoptionally the NH₃, or the second aqueous solution may be added to, forexample, brine, seawater, or freshwater, followed by the addition of thefirst aqueous solution comprising calcium salt. In another example, thegaseous stream comprising the CO₂ and optionally the NH₃, or the secondaqueous solution may be added directly to the first aqueous solutioncomprising calcium salt.

The first aqueous solution comprising calcium salt may be contacted withthe gaseous stream comprising the CO₂ and optionally the NH₃ using anyconvenient protocol. The contact protocols of interest include, but notlimited to, direct contacting protocols (e.g., bubbling the gasesthrough the first aqueous solution), concurrent contacting means (i.e.,contact between unidirectional flowing gaseous and liquid phasestreams), countercurrent means (i.e., contact between oppositely flowinggaseous and liquid phase streams), and the like. As such, contact may beaccomplished through use of infusers, bubblers, fluidic Venturireactors, spargers, gas filters, sprays, trays, or packed columnreactors, and the like, in the precipitation reactor. In someembodiments, gas-liquid contact is accomplished by forming a liquidsheet of solution with a flat jet nozzle, wherein the gases and theliquid sheet move in countercurrent, co-current, or crosscurrentdirections, or in any other suitable manner. In some embodiments,gas-liquid contact is accomplished by contacting liquid droplets of thesolution having an average diameter of 500 micrometers or less, such as100 micrometers or less, with the gas source.

In some embodiments, substantially (e.g., 80% or more or 90% or 99.9% or100%) the entire gaseous CO₂ (from the calcination) and optionally NH₃waste stream produced by step A of the process illustrated in Figsherein is employed in the precipitation of the precipitation material.In some embodiments, a portion of the gaseous CO₂ and optionally NH₃waste stream is employed in the precipitation of the precipitationmaterial and is may be 75% or less, such as 60% or less, and including50% and less of the gaseous waste stream.

Any number of the gas-liquid contacting protocols described herein maybe utilized. Gas-liquid contact or the liquid-liquid contact iscontinued until the pH of the precipitation reaction mixture is optimum(various optimum pH values have been described herein to form theprecipitation material comprising e.g. reactive vaterite), after whichthe precipitation reaction mixture is allowed to stir. The rate at whichthe pH drops may be controlled by addition of more of the first aqueoussolution comprising calcium salt during gas-liquid contact or theliquid-liquid contact. In addition, additional first aqueous solutionmay be added after sparging to raise the pH back to basic levels forprecipitation of a portion or all of the precipitation material. In anycase, the precipitation material may be formed upon removing protonsfrom certain species in the precipitation reaction mixture. Theprecipitation material comprising carbonates may then be separated and,optionally, further processed.

The rate at which the pH drops may be controlled by addition ofadditional supernatant or the first aqueous solution comprising calciumsalt during gas-liquid contact or the liquid-liquid contact. Inaddition, additional supernatant or the first aqueous solutioncomprising calcium salt may be added after gas-liquid contact or theliquid-liquid contact to raise the pH back to basic levels (e.g. between7-9 or between 7-8.5 or between 7-8 or between 8-9) for precipitation ofa portion or all of the precipitation material.

In methods and systems provided herein, the aqueous solution produced bycontacting the first aqueous solution comprising calcium salt with thegaseous stream comprising the CO₂ and optionally the NH₃ or the aqueoussolution produced by contacting the first aqueous solution comprisingcalcium salt with the second aqueous solution comprising ammoniumbicarbonate, ammonium carbonate, ammonia, (optionally ammoniumcarbamate) or combinations thereof, is subjected to the one or more ofprecipitation conditions (step C in FIGS. 1-3 ) sufficient to producethe precipitation material comprising stable or reactive vaterite or PCCand a supernatant (i.e., the part of the solution that is left overafter precipitation of the precipitation material). The one or moreprecipitation conditions favor production of the precipitation materialcomprising stable or reactive vaterite or PCC.

The one or more precipitation conditions include those that modulate theenvironment of the precipitation reaction mixture to produce the desiredprecipitation material comprising stable or reactive vaterite or PCC.Such one or more precipitation conditions, that can be used in themethod and system aspects and embodiments described herein, suitable toform stable or reactive vaterite or PCC containing precipitationmaterial include, but not limited to, temperature, pH, pressure, ionratio, precipitation rate, presence of additive, presence of ionicspecies, concentration of additive and ionic species, stirring,residence time, mixing rate, forms of agitation such as ultrasonics,presence of seed crystals, catalysts, membranes, or substrates,dewatering, drying, ball milling, etc. In some embodiments, the averageparticle size of the stable or the reactive vaterite or PCC may alsodepend on the one or more precipitation conditions used in theprecipitation of the precipitation material. In some embodiments, thepercentage of the stable or the reactive vaterite in the precipitationmaterial may also depend on the one or more precipitation conditionsused in the precipitation process.

For example, the temperature of the precipitation reaction may be raisedto a point at which an amount suitable for precipitation of the desiredprecipitation material occurs. In such embodiments, the temperature ofthe precipitation reaction may be raised to a value, such as from 20° C.to 60° C., and including from 25° C. to 60° C.; or from 30° C. to 60°C.; or from 35° C. to 60° C.; or from 40° C. to 60° C.; or from 50° C.to 60° C.; or from 25° C. to 50° C.; or from 30° C. to 50° C.; or from35° C. to 50° C.; or from 40° C. to 50° C.; or from 25° C. to 40° C.; orfrom 30° C. to 40° C.; or from 25° C. to 30° C. In some embodiments, thetemperature of the precipitation reaction may be raised using energygenerated from low or zero carbon dioxide emission sources (e.g., solarenergy source, wind energy source, hydroelectric energy source, wasteheat from the flue gases of the carbon emitter, etc).

The pH of the precipitation reaction may also be raised to an amountsuitable for the precipitation of the desired precipitation material. Insuch embodiments, the pH of the precipitation reaction may be raised toalkaline levels for precipitation. In some embodiments, the pH of thefirst aqueous solution comprising calcium salt that is contacted withthe gaseous stream comprising the carbon dioxide gas and optionally theNH₃ gas (or with the second aqueous solution) has an effect on theformation of the stable or reactive vaterite or PCC. In someembodiments, the precipitation conditions required to form theprecipitation material include conducting the precipitation step of thegaseous stream comprising the carbon dioxide gas and optionally the NH₃gas (or the second aqueous solution) with the first aqueous solutioncomprising calcium salt at pH higher than 7 or pH of 8 or pH of between7.1-8.5 or pH of between 7.5-8 or between 7.5-8.5 or between 8-8.5 orbetween 8-9 or between 7.6-8.4, in order to form the precipitationmaterial. The pH may be raised to pH 9 or higher, such as pH 10 orhigher, including pH 11 or higher or pH 12.5 or higher.

Adjusting major ion ratios during precipitation may influence the natureof the precipitation material. Major ion ratios may have considerableinfluence on polymorph formation. For example, as the magnesium:calciumratio in the water increases, aragonite may become the major polymorphof calcium carbonate in the precipitation material over low-magnesiumvaterite. At low magnesium:calcium ratios, low-magnesium calcite maybecome the major polymorph. In some embodiments, where Ca²⁺ and Mg²⁺ areboth present, the ratio of Ca²⁺ to Mg²⁺ (i.e., Ca²⁺:Mg²⁺) in theprecipitation material is 1:1 to 1:2.5; 1:2.5 to 1:5; 1:5 to 1:10; 1:10to 1:25; 1:25 to 1:50; 1:50 to 1:100; 1:100 to 1:150; 1:150 to 1:200;1:200 to 1:250; 1:250 to 1:500; or 1:500 to 1:1000. In some embodiments,the ratio of Mg²⁺ to Ca²⁺ (i.e., Mg²⁺:Ca²⁺) in the precipitationmaterial is 1:1 to 1:2.5; 1:2.5 to 1:5; 1:5 to 1:10; 1:10 to 1:25; 1:25to 1:50; 1:50 to 1:100; 1:100 to 1:150; 1:150 to 1:200; 1:200 to 1:250;1:250 to 1:500; or 1:500 to 1:1000.

Precipitation rate may also have an effect on precipitation materialformation, with the most rapid precipitation rate achieved by seedingthe solution with a desired phase. Without seeding, rapid precipitationmay be achieved by rapidly increasing the pH of the precipitationreaction mixture, which may result in more amorphous constituents. Thehigher the pH, the more rapid is the precipitation, which may result ina more amorphous precipitation material.

Residence time of the precipitation reaction after contacting the firstaqueous solution with the gaseous stream comprising the carbon dioxidegas and optionally the NH₃ gas (or with the second aqueous solution) mayalso have an effect on precipitation material formation. For example, insome embodiments, a longer residence time may result in transformationof the reactive vaterite to aragonite/calcite within the reactionmixture. In some embodiments, too short residence time may result in anincomplete formation of the reactive vaterite in the reaction mixture.Therefore, the residence time may be critical to the precipitation ofthe reactive vaterite. Further, the residence time may also affect theparticle size of the precipitate. For example, too long residence timemay result in the agglomeration of the particles forming large sizeparticles which is undesirable for PCC formation. Therefore, in someembodiments, the residence time of the reaction is between about 5-60minutes, or between about 5-15 minutes, or between about 10-60 minutes,or between about 15-60 min, or between about 15-45 min, or between about15-30 min, or between about 30-60 min.

In some embodiments, the one or more precipitation conditions to producethe desired precipitation material from the precipitation reaction mayinclude, as above, the temperature and pH, as well as, in someinstances, the concentrations of additives and ionic species in thewater. The additives have been described herein below. The presence ofthe additives and the concentration of the additives may also favorformation of stable or reactive vaterite or PCC. In some embodiments, amiddle chain or long chain fatty acid ester may be added to the firstaqueous solution during the precipitation to form the PCC. Examples offatty acid esters include, without limitation, cellulose such ascarboxymethyl cellulose, sorbitol, citrate such as sodium or potassiumcitrate, stearate such as sodium or potassium stearate, phosphate suchas sodium or potassium phosphate, sodium tripolyphosphate,hexametaphosphate, EDTA, or combinations thereof. In some embodiments, acombination of stearate and citrate may be added during theprecipitation step of the process to form the PCC.

The one or more precipitation conditions may also include factors suchas mixing rate, forms of agitation such as ultrasonics, and the presenceof seed crystals, catalysts, membranes, or substrates. In someembodiments, the one or more precipitation conditions includesupersaturated conditions, temperature, pH, and/or concentrationgradients, or cycling or changing any of these parameters. The protocolsemployed to prepare the precipitation material may be batch, semi-batch,or continuous protocols. The one or more precipitation conditions may bedifferent to produce the precipitation material in a continuous flowsystem compared to a semi-batch or batch system.

In some embodiments of the methods and systems provided herein, theformation of the precipitation material comprising stable or reactivevaterite can be facilitated on a surface of an aggregate. In someembodiments of the methods and systems provided herein, where theaqueous solution is produced under the one or more of precipitationconditions (step C in FIGS. 1-3 ) by contacting the first aqueoussolution comprising calcium salt with the gaseous stream comprising theCO₂ and optionally the NH₃, or the aqueous solution produced bycontacting the first aqueous solution comprising calcium salt with thesecond aqueous solution comprising ammonium bicarbonate, ammoniumcarbonate, ammonia, (optionally ammonium carbamate) or combinationsthereof; the methods and systems further comprise adding an aggregate tothe aqueous solution and forming the precipitation material comprisingstable or reactive vaterite on the surface of the aggregate.

The term “aggregate” as used herein includes a particulate compositionthat finds use in concretes, mortars and other materials, e.g.,roadbeds, asphalts, and other structures and is suitable for use in suchstructures. Aggregates are particulate compositions that may in someembodiments be classified as fine or coarse. Fine aggregates generallyinclude natural sand or crushed stone with most particles passingthrough a ⅜-inch sieve. Coarse aggregates generally are any particlesgreater than 0.19 inch, but generally range between ⅜ and 1.5 inches indiameter. Gravels may constitute the coarse aggregate used in concretewith crushed stone making up the remainder. In some embodiments, theaggregate is crushed lime rock. In some embodiments, the aggregate isrepurposed or reused concrete. The methods and systems provided hereinadd recyclability or value (by having better bonding characteristics) toconcrete repurposed from old projects.

In the aforementioned methods and systems, when the aggregate is addedto the precipitation step C, the precipitation material forms an outerlayer surrounding the surface of the aggregate thereby activating thesurface of the inert aggregate material. This activated surface of theaggregate (comprising the reactive vaterite) coming in contact withwater (the process of dissolution-reprecipitation of the vaterite toaragonite explained herein below) and cement, transforms vaterite to thearagonite which binds to the cement. The aggregate thus activatedprovides better binding to the cement.

Therefore, in some embodiments, there are provided methods to formcalcium carbonate comprising vaterite, comprising:

(i) calcining limestone to form lime and a gaseous stream comprisingcarbon dioxide;

(ii) dissolving the lime in an aqueous base solution under one or moredissolution conditions to produce a first aqueous solution comprisingcalcium salt, and a gaseous stream comprising ammonia;

(iii) adding an aggregate to the first aqueous solution; and

(iv) treating the first aqueous solution comprising calcium salt and theaggregate with the gaseous stream comprising carbon dioxide and thegaseous stream comprising ammonia under one or more precipitationconditions to form a precipitation material comprising calcium carbonateon a surface of the aggregate, wherein the calcium carbonate comprisesvaterite.

In some embodiments, there are provided methods to form calciumcarbonate comprising vaterite, comprising:

(i) calcining limestone to form lime and a gaseous stream comprisingcarbon dioxide;

(ii) dissolving the lime in an aqueous N-containing inorganic saltsolution under one or more dissolution conditions to produce a firstaqueous solution comprising calcium salt, and a gaseous streamcomprising ammonia;

(iii) recovering the gaseous stream comprising carbon dioxide and thegaseous stream comprising ammonia and subjecting the gaseous streams toa cooling process under one or more cooling conditions to condense asecond aqueous solution comprising ammonium bicarbonate, ammoniumcarbonate, ammonia, or combinations thereof;

(iv) adding an aggregate to the first aqueous solution; and

(v) treating the first aqueous solution comprising calcium salt and theaggregate with the second aqueous solution comprising ammoniumbicarbonate, ammonium carbonate, ammonia, or combinations thereof underone or more precipitation conditions to form a precipitation materialcomprising calcium carbonate on a surface of the aggregate, wherein thecalcium carbonate comprises vaterite.

In some embodiments of the aforementioned embodiments, the secondaqueous solution further comprises ammonium carbamate. It is to beunderstood that while the precipitation material comprising calciumcarbonate is formed on the surface of the aggregate, some precipitationmaterial may be formed in the aqueous solution which is separated fromthe supernatant solution along with the activated aggregate. In someembodiments, the amount of the first aqueous solution comprising calciumsalt in the precipitation reactor may be optimized to selectivelyprecipitate the reactive vaterite on the surface of the aggregate, orselectively precipitate the precipitation material in the aqueoussolution, or both. In the aforementioned methods and systems, theprecipitation material comprising calcium carbonate comprises reactivevaterite. In the aforementioned methods and systems, the aggregate maybe the fine aggregate or the coarse aggregate. In some embodiments ofthe aforementioned methods and systems, the aggregate is the samelimestone used in step (i) of the process or may be a crushed form ofthe limestone of step (i).

In some embodiments, the gas leaving the precipitation reactor (shown as“scrubbed gas” in FIGS. 1-3 ) passes to a gas treatment unit for ascrubbing process. The mass balance and equipment design for the gastreatment unit may depend on the properties of the gases. In someembodiments, the gas treatment unit may incorporate an HCl scrubber forrecovering the small amounts of NH₃ in the gas exhaust stream that maybe carried from the CO₂ absorption, precipitation step by the gas. NH₃may be captured by the HCl solution through:NH₃(g)+HCl(aq)→NH₄Cl(aq)

The NH₄Cl (aq) from the HCl scrubber may be recycled to the dissolutionstep A.

In some embodiments, the gas exhaust stream comprising ammonia (shown as“scrubbed gas” in FIGS. 1-3 ) may be subjected to a scrubbing processwhere the gas exhaust stream comprising ammonia is scrubbed with thecarbon dioxide from the industrial process and water to produce asolution of ammonia. The inlets for the scrubber may be carbon dioxide(CO_(2(g))), the reactor gas exhaust containing ammonia (NH_(3(g)), andfresh makeup water (or some other dilute water stream). The outlet maybe a slipstream of the scrubber's recirculating fluid (e.g.H₃N—CO_(2(aq)) or carbamate), which may optionally be returned back tothe main reactor for contacting with carbon dioxide and precipitation.The pH of the system may be controlled by regulating the flow rate ofCO_(2(g)) into the scrubber. The conductivity of the system may becontrolled by addition of dilute makeup water to the scrubber. Volumemay be maintained constant by using a level detector in the scrubber orit's reservoir. While ammonia is a basic gas, the carbon dioxide gasesare acidic gases. In some embodiments, the acidic and basic gases mayionize each other to increase their solubilities.

Without being limited by any theory, it is contemplated that thefollowing reaction may take place in the scrubber:NH₃(aq)+CO₂(aq)+H₂O→HCO₃ ⁻+NH₄ ⁺

The first aqueous solution comprising calcium salt when contacted withthe gaseous stream comprising CO₂ gas and optionally the NH₃ gas (orwith the second aqueous solution) under one or more precipitationconditions results in the precipitation of the calcium carbonate. Theone or more precipitation conditions that result in the formation of thestable or reactive vaterite or PCC in this process have been describedherein below.

In some embodiments, the precipitation material comprises stablevaterite and/or reactive vaterite or PCC. The “stable vaterite” or itsgrammatical equivalent as used herein includes vaterite that does nottransform to aragonite or calcite during and/or afterdissolution-reprecipitation process in water. The “reactive vaterite” or“activated vaterite” or its grammatical equivalent as used herein,includes vaterite that results in aragonite formation during and/orafter dissolution-re-precipitation process in water. The “precipitatedcalcium carbonate” or “PCC” as used herein includes conventional PCCwith high purity and micron or lesser size particles. The PCC can be inany polymorphic form of calcium carbonate including but not limited tovaterite, aragonite, calcite, or combination thereof. In someembodiments, the PCC has a particle size in nanometers or between0.001-5 micron.

In some embodiments, the vaterite in the precipitation material and/oron the surface of the aggregate may be formed under suitable conditionsso that the vaterite is reactive and transforms to aragonite upondissolution-precipitation process (during cementation) in water. Thearagonite may impart one or more unique characteristics to the productincluding, but not limited to, high compressive strength, complexmicrostructure network, neutral pH etc. In some embodiments, thevaterite in the precipitation material may be formed under suitableconditions so that the vaterite is stable and is used as filler invarious applications. In some embodiments, the PCC in the precipitationmaterial may be formed under suitable conditions so that the PCC ishighly pure and is of a very small size particle.

The precipitation material comprising reactive vaterite (optionallyincluding solids as described herein) undergoes transformation toaragonite and sets and hardens into cementitious products (shown asproducts (A) in FIGS. 1-3 ), the solids may get incorporated in thecementitious products. This provides an additional advantage of one lessstep of removal of the solids, minimizing the loss of the base, such ase.g. NH₄Cl loss as well as eliminating a potential waste stream therebyincreasing the efficiency and improving the economics of the process. Insome embodiments, the solid impurities do not adversely affect thetransformation and/or reactivity of the vaterite to aragonite. In someembodiments, the solid impurities do not adversely affect the strength(such as compressive strength or flexural strength) of the cementitiousproducts.

In some embodiments, the methods and systems provided herein furtherinclude separating the precipitation material (step D in FIGS. 1-3 )from the aqueous solution by dewatering to form calcium carbonate cake(as shown in FIGS. 1-3 ). The calcium carbonate cake may be subjectedoptionally to rinsing, and optionally drying (step E in FIGS. 1-3 ). Thedried precipitated material or the dried calcium carbonate cake may thenbe used to make cementitious or non-cementitious products (shown asproducts (B) in FIGS. 1-3 ). In some embodiments, the calcium carbonatecake may contain impurities (e.g., 1-2% by weight or more) of ammonium(NH₄ ⁺) ions, sulfur ions, and/or chloride (Cl⁻) ions. While rinsing ofthe calcium carbonate cake may remove some or all of the ammonium saltsand/or sulfur compounds, it may result in a dilute concentration ofammonium salts (in the supernatant) which may need concentrating beforerecycling it back to the process.

The methods and systems provided herein may result in residual base suchas the residual N-containing inorganic or N-containing organic salt,e.g. residual ammonium salt remaining in the supernatant solution aswell as in the precipitate itself after the formation of theprecipitate. The residual base such as the N-containing inorganic orN-containing organic salt, e.g. residual ammonium salt (e.g. residualNH₄Cl) as used herein includes any salt that may be formed by ammoniumions and anions present in the solution including, but not limited tohalogen ions such as chloride ions, nitrate or nitrite ions, and sulfurions such as, sulfate ions, sulfite ions, thiosulfate ions, hydrosulfideions, and the like. In some embodiments, the residual N-containinginorganic salt comprises ammonium halide, ammonium sulfate, ammoniumsulfite, ammonium hydrosulfide, ammonium thiosulfate, ammonium nitrate,ammonium nitrite, or combinations thereof. Various methods have beenprovided herein to remove and optionally recover the residual salt fromthe supernatant solution as well as the precipitate. In someembodiments, the supernatant solution further comprising theN-containing inorganic or N-containing organic salt, e.g. residualammonium salt (e.g. residual NH₄Cl), is recycled back to the dissolutionreactor for the dissolution of the lime (to step A in FIGS. 1-3 ).

The residual base solution such as the N-containing inorganic orN-containing organic salt solution, e.g. residual ammonium salt solution(e.g. residual NH₄Cl) obtained from the dewatering as well as therinsing stream may optionally be concentrated before being recycled backfor the dissolution of the lime. Additional base, such as e.g. ammoniumchloride and/or ammonia (anhydrous or aqueous solution) may be added tothe recycled solution to make up for the loss of the ammonium chlorideduring the process and bring the concentration of ammonium chloride tothe optimum level.

In some embodiments, the residual N-containing inorganic or N-containingorganic salt solution, e.g. residual ammonium salt solution (e.g.residual NH₄Cl), as illustrated in FIGS. 1-3 , may be recovered from thesupernatant aqueous solution and concentrated using recovery process,such as, but not limited to, thermal decomposition, pH adjustment,reverse osmosis, multi-stage flash, multi-effect distillation, vaporrecompression, distillation, or combinations thereof. The systemsconfigured to carry out these processes are available commercially. Forexample, the pH of the solution may be raised (e.g. with a strong baselike NaOH). This may shift the equilibrium towards volatile ammonia(NH₃(aq)/NH₃(g)). Rates and total removal could both be improved byheating the solution.

In some embodiments, the residual N-containing inorganic or N-containingorganic salt solution, e.g. residual ammonium salt solution (e.g.residual NH₄Cl) may be separated and recovered from the precipitate bythe thermal decomposition process. This process may be incorporated inthe processes illustrated in FIGS. 1-3 at the separation of the CaCO₃precipitate (step D) and/or after the step of the dried CaCO₃precipitate or powder (step E).

Typically, at 338° C., solid NH₄Cl may decompose into ammonia (NH₃) andhydrogen chloride (HCl) gases. While at 840° C., solid CaCO₃ decomposesto calcium oxide (CaO) solid and carbon dioxide (CO₂) gas.NH₄Cl_((s))↔NH_(3(g))+HCl_((g))CaCO_(3(s))↔CaO_((s))+CO_(2(g))

In some embodiments, the residual ammonium salt in the CaCO₃ precipitateand/or dried CaCO₃ precipitate such as, but not limited to, ammoniumchloride, ammonium sulfate, ammonium sulfite, ammonium hydrosulfide,ammonium thiosulfate, ammonium nitrate, ammonium nitrite, orcombinations thereof may be removed by thermal decomposition at atemperature between 338-840° C. This may be done either during thenormal filter cake drying process and/or as a second post-drying heattreatment. A temperature range is desirable that decomposes residualammonium salts in the precipitation while preserving the cementitiousproperties of the reactive vaterite in the precipitation material suchthat the reactive vaterite stays as reactive vaterite after heating, andafter combination with water, successfully transforms to aragonite toform cementitious products.

In some embodiments of the foregoing aspect and embodiments, the step ofremoving and optionally recovering the residual N-containing inorganicor N-containing organic salt, such as e.g. ammonium salt from theprecipitation material comprises heating the precipitation materialbetween about 290-375° C. or between about 300-360° C. or between about300-350° C. or between about 310-345° C. or between about 320-345° C. orbetween about 330-345° C. or between about 300-345° C., to evaporate theresidual N-containing inorganic or N-containing organic salt from theprecipitation material with optional recovery by condensation of theresidual N-containing inorganic or N-containing organic salt.

In some embodiments of the foregoing aspect and embodiments, the step ofremoving and optionally recovering the residual N-containing inorganicor N-containing organic salt, such as e.g. residual ammonium salt fromthe precipitation material comprises heating the precipitation material,for a duration of more than about 10 min or of more than about 15 min orfor than about 5 min or of between about 10 min to about 1 hour or ofbetween about 10 min to about 1.5 hour or of between about 10 min toabout 2 hours or of between about 10 min to about 5 hours or of betweenabout 10 min to about 10 hours.

In some embodiments, the precipitation material is dewatered (to removethe supernatant aqueous solution) and dried to remove water (e.g. byheating at about or above 100° C.) before subjecting the precipitationmaterial to the heating step as above to remove and optionally recoverthe residual N-containing inorganic or N-containing organic salt, e.g.residual ammonium salt. In some embodiments, the precipitation materialis partially dewatered (to remove bulk of the supernatant aqueoussolution) and partially dried to remove water (or avoid the drying step)before subjecting the precipitation material to the heating step toremove and optionally recover the residual N-containing inorganic orN-containing organic salt, e.g. residual ammonium salt. In someembodiments, the reactive vaterite in the precipitation material staysas reactive vaterite after heating. In some embodiments of the foregoingembodiments, it is desirable that the reactive vaterite in theprecipitation material stays as reactive vaterite such that thecementitious properties of the material are conserved. In someembodiments, the ammonium salt evaporates from the precipitationmaterial in a form comprising ammonia gas, hydrogen chloride gas,chlorine gas, or combinations thereof. Applicants have found that insome embodiments, maintaining a combination of the amount of temperatureand duration of heating may be critical to removing ammonium salt fromthe precipitation material yet preserving the cementitious properties ofthe reactive vaterite material. Traditionally, the reactive vaterite ishighly unstable and transforms readily to aragonite/calcite. However,Applicants have found temperature ranges coupled optionally withduration of heating that minimize the transformation of the reactivevaterite yet remove residual ammonium salts from the material. In someembodiments of the foregoing embodiments, the vaterite in theprecipitation material, after removal of the residual N-containinginorganic or N-containing organic salt, e.g. residual ammonium salt,stays as reactive vaterite which when combined with water transforms toaragonite (dissolution-reprecipitation process) which sets and cementsto form cementitious products. The cementitious products, thus formed,possess minimal or no chloride content and have no foul smell of ammoniaor sulfur. In some embodiments, the chloride content is around or belowacceptable ASTM standards for the cementitious products.

In some embodiments, the above recited temperature conditions optionallycoupled with duration of heating, may be combined with pressureconditions that provide a driving force to improve the thermodynamics ofthe decomposition of the residual N-containing inorganic or N-containingorganic salt, e.g. residual ammonium salt. For example, the heating ofthe precipitation material may be carried out in a system in which theheadspace is at a pressure lower than atmospheric pressure. The pressurelower than the atm pressure may create a driving force for heatingreaction that involves gas phase products (such as, but not limited to,ammonia gas, hydrogen chloride gas, chlorine gas, or combinationsthereof), by reducing the partial pressure of the reactant in the vaporphase. Another advantage of operating under reduced pressure or vacuummay be that at lower pressure some sublimation reactions may occur atlower temperatures thereby improving the energy requirements of theheating reaction.

In some embodiments of the above described thermal decompositionprocess, the separated ammonium chloride in the form of ammonia and HClgases, may be recovered for reuse by either recrystallization of thecombined thermally evolved gases or by absorbing the gases into anaqueous medium. Both mechanisms may result in the NH₄Cl product that maybe concentrated enough for reuse in the processes as shown in FIGS. 1-3.

In some embodiments, the ammonium salt may be separated and recovered inthe above described process by pH adjusted evolution of the NH₃ gas fromthe ammonium salt. This process may be incorporated in the processesillustrated in FIGS. 1-3 at the separation of the CaCO₃ cake. The finalpH of the water in the filter cake may typically be about 7.5. At thispH, NH₄ ⁺ (pKa=9.25) may be the predominant species. Increasing the pHof this water may drive the acid base equilibrium toward NH₃ gas, asdescribed in the following equation:NH₄ ⁺↔H⁺+NH_(3(g))

Any source of alkalinity may be used to increase the pH of the filtercake water. In some embodiments, the aqueous solution of the calciumoxide and/or hydroxide or the lime slurry may provide the source of highalkalinity. In some embodiments, the aqueous fraction of the lime may beintegrated into the rinsing stage of the dewatering process (e.g. filtercake step) to raise the pH of the system, and drive the evolution of NH₃gas. As ammonia has substantial solubility in water, heat and/or vacuumpressure may be applied to drive the equilibrium further toward thegaseous phase. The ammonia may be recovered for reuse by eitherrecrystallization of ammonia with chloride or by absorbing the ammoniainto an aqueous medium. Both mechanisms may result in the ammoniasolution or NH₄Cl product that may be concentrated enough for reuse inthe processes described in FIGS. 1-3 .

The calcium carbonate cake (e.g. vaterite or PCC) may be sent to thedryer (step E in FIG. 1 ) to form calcium carbonate powder containingstable or reactive vaterite or PCC. The powder form of the precipitationmaterial comprising stable or reactive vaterite or PCC may be usedfurther in applications to form products, as described herein. The cakemay be dried using any drying techniques known in the art such as, butnot limited to fluid bed dryer or swirl fluidizer. The resulting solidpowder may be then mixed with additives to make different productsdescribed herein. In some embodiments, the slurry form with reducedwater or the cake form of the precipitation material is directly used toform products, such as construction panel, as described herein.

Optionally the solids separated, may be dried and used as a pozzolan. Insome embodiments, the solids separated may be added to the powder formof the precipitation material comprising vaterite as filler orsupplementary cementitious material.

In the systems provided herein, the separation or dewatering step D maybe carried out on the separation station. The precipitation material maybe stored in the supernatant for a period of time followingprecipitation and prior to separation. For example, the precipitationmaterial may be stored in the supernatant for a period of time rangingfrom few min to hours to 1 to 1000 days or longer, such as 1 to 10 daysor longer, at a temperature ranging from 1° C. to 40° C., such as 20° C.to 25° C. Separation or dewatering of the precipitation material fromthe precipitation reaction mixture may be achieved using any of a numberof convenient approaches, including draining (e.g., gravitationalsedimentation of the precipitation material followed by draining),decanting, filtering (e.g., gravity filtration, vacuum filtration,filtration using forced air), centrifuging, pressing, or any combinationthereof. Separation of the bulk water from the precipitation materialproduces a wet cake of precipitation material, or a dewateredprecipitation material. Liquid-solid separator such as Epuramat'sExtrem-Separator (“ExSep”) liquid-solid separator, Xerox PARC's spiralconcentrator, or a modification of either of Epuramat's ExSep or XeroxPARC's spiral concentrator, may be useful for the separation of theprecipitation material from the precipitation reaction.

In some embodiments, the resultant dewatered precipitation material suchas the wet cake material (after e.g. thermally removing the N-containingsalt) may be directly used to make the products (A) described herein.For example, the wet cake of the dewatered precipitation material ismixed with one or more additives, described herein, and is spread out onthe conveyer belt where the reactive vaterite or PCC in theprecipitation material transforms to aragonite and sets and hardens (andammonium salt gets thermally removed). The hardened material is then cutinto desired shapes such as boards or panels described herein. In someembodiments, the wet cake is poured onto a sheet of paper on top of theconveyer belt. Another sheet of paper may be put on top of the wet cakewhich is then pressed to remove excess water. After the setting andhardening of the precipitation material (vaterite transformation toaragonite), the material is cut into desired shapes, such as, cementsiding boards and drywall etc. In some embodiments, the amount of theone or more additives may be optimized depending on the desired timerequired for the transformation of the vaterite to aragonite (describedbelow). For example, for some applications, it may be desired that thematerial transform rapidly and in certain other instance, a slowtransformation may be desired. In some embodiments, the wet cake may beheated on the conveyer belt to hasten the transformation of the vateriteto aragonite. In some embodiments, the wet cake may be poured in themolds of desired shape and the molds are then heated in the autoclave tohasten the transformation of the vaterite to aragonite (and to removeresidual salt). Accordingly, the continuous flow process, batch processor semi-batch process, all are well within the scope of the invention.

In some embodiments, the precipitation material comprising vaterite,once separated from the precipitation reaction, is washed with freshwater, and then placed into a filter press to produce a filter cake with30-60% solids. This filter cake is then mechanically pressed in a mold,using any convenient means, e.g., a hydraulic press, at adequatepressures, e.g., ranging from 5 to 5000 psi, such as 1000 to 5000 psi,to produce a formed solid, e.g., a rectangular brick. These resultantsolids are then cured, e.g., by placing outside and storing, by placingin a chamber wherein they are subjected to high levels of humidity andheat, etc. These resultant cured solids are then used as buildingmaterials themselves or crushed to produce aggregate.

In processes involving the use of temperature and pressure, thedewatered precipitate cake may be dried. The cake is then exposed to acombination of rewatering, and elevated temperature and/or pressure fora certain time. The combination of the amount of water added back, thetemperature, the pressure, and the time of exposure, as well as thethickness of the cake, can be varied according to composition of thestarting material and the desired results.

A number of different ways of exposing the material to temperature andpressure are described herein; it will be appreciated that anyconvenient method may be used. Thickness and size of the cake may beadjusted as desired; the thickness can vary in some embodiment from 0.05inch to 5 inches, e.g. 0.1-2 inches, or 0.3-1 inch. In some embodimentsthe cake may be 0.5 inch to 6 feet or even thicker. The cake is thenexposed to elevated temperature and/or pressure for a given time, by anyconvenient method, for example, in a platen press using heated platens.The heat to elevate the temperature, e.g., for the platens, may beprovided, e.g., by heat from an industrial waste gas stream such as aflue gas stream. The temperature may be any suitable temperature; ingeneral, for a thicker cake a higher temperature is desired; examples oftemperature ranges are 40-150° C., e.g., 60-120° C., such as 70-110° C.,or 80-100° C. Similarly, the pressure may be any suitable pressure toproduce the desired results; exemplary pressures include 1000-100,000pounds per square inch (psi), including 2000-50,000 psi, or 2000-25,000psi, or 2000-20,000 psi, or 3000-5000 psi. Finally, the time that thecake is pressed may be any suitable time, e.g., 1-100 seconds, or 1-100minute, or 1-50 minutes, or 2-25 minutes, or 1-10,000 days. Theresultant hard tablet may optionally then cured, e.g., by placingoutside and storing, by placing in a chamber wherein they are subjectedto high levels of humidity and heat, etc. These hard tablets, optionallycured, are then used as building materials themselves or crushed toproduce aggregate.

Another method of providing temperature and pressure is the use of apress. A suitable press, e.g., a platen press, may be used to providepressure at the desired temperature (using heat supplied, e.g., by aflue gas or by other steps of the process to produce a precipitate,e.g., from an electrochemical process) for a desired time. A set ofrollers may be used in similar fashion.

Another way to expose the cake to elevated temperature and pressure isby means of an extruder, e.g., a screw-type extruder. The barrel of theextruder can be outfitted to achieve an elevated temperature, e.g., byjacketing; this elevated temperature can be supplied by, e.g., fluegases or the like. Extrusion may be used as a means of pre-heating anddrying the feedstock prior to a pressing operation. Such pressing can beperformed by means of a compression mold, via rollers, via rollers withshaped indentations (which can provide virtually any shape of aggregatedesired), between a belt which provides compression as it travels, orany other convenient method. Alternatively, the extruder may be used toextrude material through a die, exposing the material to pressure as itis forced through the die, and giving any desired shape. In someembodiments, the carbonate precipitate is mixed with fresh water andthen placed into the feed section of a rotating screw extruder. Theextruder and/or the exit die may be heated to further assist in theprocess. The turning of the screw conveys the material along its lengthand compresses it as the flute depth of the screw decreases. The screwand barrel of the extruder may further include vents in the barrel withdecompression zones in the screw coincident with the barrel ventopenings. Particularly in the case of a heated extruder, these ventedareas allow for the release of steam from the conveyed mass, removingwater from the material.

The screw conveyed material is then forced through a die section whichfurther compresses the material and shapes it. Typical openings in thedie can be circular, oval, square, rectangular, trapezoidal, etc.,although any shape which the final aggregate is desired in could be madeby adjusting the shape of the opening. The material exiting the die maybe cut to any convenient length by any convenient method, such as by afly knife. Use of a heated die section may further assist in theformation of the product by accelerating the transition of the carbonatemineral to a hard, stable form. Heated dies may also be used in the caseof binders to harden or set the binder. Temperatures of 100° C. to 600°C. are commonly used in the heated die section.

In yet other embodiments, the precipitate may be employed for in situ orform-in-place structure fabrication. For example, roads, paved areas, orother structures may be fabricated from the precipitate by applying alayer of precipitate, e.g., as described above, to a substrate, e.g.,ground, roadbed, etc., and then hydrating the precipitate, e.g., byallowing it to be exposed to naturally applied water, such as in theform of rain, or by irrigation. Hydration solidifies the precipitateinto a desired in situ or form-in-place structure, e.g., road, pavedover area, etc. The process may be repeated, e.g., where thicker layersof in-situ formed structures are desired.

In some embodiments, the production of the precipitation material andthe products is carried out in the same facility. In some embodiments,the precipitation material is produced in one facility and istransported to another facility to make the end product. Theprecipitation material may be transported in the slurry form, wet cakeform, or dry powder form.

In some embodiments, the resultant dewatered precipitation materialobtained from the separation station is dried at the drying station toproduce a powder form of the precipitation material comprising stable orreactive vaterite or PCC. Drying may be achieved by air-drying theprecipitation material. In certain embodiments, drying is achieved byfreeze-drying (i.e., lyophilization), wherein the precipitation materialis frozen, the surrounding pressure is reduced, and enough heat is addedto allow the frozen water in the precipitation material to sublimedirectly into gas. In yet another embodiment, the precipitation materialis spray-dried to dry the precipitation material, wherein the liquidcontaining the precipitation material is dried by feeding it through ahot gas (such as the gaseous waste stream from the power plant), andwherein the liquid feed is pumped through an atomizer into a main dryingchamber and a hot gas is passed as a co-current or countercurrent to theatomizer direction. Depending on the particular drying protocol of thesystem, the drying station may include a filtration element,freeze-drying structure, spray-drying structure, etc. In someembodiments, the precipitate may be dried by fluid bed dryer. In certainembodiments, waste heat from a power plant or similar operation may beused to perform the drying step when appropriate. For example, in someembodiments, dry product is produced by the use of elevated temperature(e.g., from power plant waste heat), pressure, or a combination thereof.Following the drying of the precipitation material, the material may bethen subjected to heating at elevated temperatures to remove theresidual N-containing salts, e.g. residual ammonium salts as describedherein.

The resultant supernatant of the precipitation process, or slurry ofprecipitation material may also be processed as desired. For example,the supernatant or slurry may be returned to the first aqueous solution,or to another location. In some embodiments, the supernatant may becontacted with the gaseous stream comprising CO₂ and optionally ammoniagas, as described herein, to sequester additional CO₂. For example, inembodiments in which the supernatant is to be returned to theprecipitation reactor, the supernatant may be contacted with the gaseousstream of CO₂ and optionally ammonia gas in a manner sufficient toincrease the concentration of carbonate ion present in the supernatant.As described above, contact may be conducted using any convenientprotocol. In some embodiments, the supernatant has an alkaline pH, andcontact with the CO₂ gas is carried out in a manner sufficient to reducethe pH to a range between pH 5 and 9, pH 6 and 8.5, or pH 7.5 to 8.7.

In some embodiments, the precipitation material produced by methodsprovided herein, is employed as a building material (e.g., aconstruction material for some type of man-made structure such asbuildings, roads, bridges, dams, and the like), such that CO₂ iseffectively sequestered in the built environment. Any man madestructure, such as foundations, parking structures, houses, officebuildings, commercial offices, governmental buildings, infrastructures(e.g., pavements; roads; bridges; overpasses; walls; footings for gates,fences and poles; and the like) is considered a part of the builtenvironment. Mortars find use in binding construction blocks (e.g.,bricks) together and filling gaps between construction blocks. Mortarscan also be used to fix existing structure (e.g., to replace sectionswhere the original mortar has become compromised or eroded), among otheruses.

In some embodiments, the powder form of the precipitation materialcomprising reactive vaterite is employed as cement, which transforms toaragonite (the dissolution-re-precipitation process) and sets andhardens after combining with water. In some embodiments, theprecipitation material comprising reactive vaterite on the surface ofthe aggregate is transformed to the aragonite (thedissolution-re-precipitation process) after combining with water andbinds to the cement that is mixed with it.

In some embodiments, an aggregate itself is produced from the resultantprecipitation material. In such embodiments, where the drying processproduces particles of the desired size, little if any additionalprocessing is required to produce the aggregate. In yet otherembodiments, further processing of the precipitation material isperformed in order to produce the desired aggregate. For example, theprecipitation material may be combined with fresh water in a mannersufficient to cause the precipitate to form a solid product, where thereactive vaterite converts to aragonite. By controlling the watercontent of the wet material, the porosity, and eventual strength anddensity of the final aggregate may be controlled. Typically a wet cakemay be 40-60 volume % water. For denser aggregates, the wet cake may be<50% water, for less dense cakes, the wet cake may be >50% water. Afterhardening, the resultant solid product may then be mechanicallyprocessed, e.g., crushed or otherwise broken up and sorted to produceaggregate of the desired characteristics, e.g., size, particular shape,etc. In these processes the setting and mechanical processing steps maybe performed in a substantially continuous fashion or at separate times.In certain embodiments, large volumes of precipitate may be stored inthe open environment where the precipitate is exposed to the atmosphere.For the setting step, the precipitate may be irrigated in a convenientfashion with fresh water, or allowed to be rained on naturally in orderto produce the set product. The set product may then be mechanicallyprocessed as described above. Following production of the precipitate,the precipitate is processed to produce the desired aggregate. In someembodiment the precipitate may be left outdoors, where rainwater can beused as the freshwater source, to cause the meteoric water stabilizationreaction to occur, hardening the precipitate to form aggregate.

The precipitate or the precipitation material formed in the methods andsystems herein after the optional removal of the residual salt comprisesvaterite or PCC. The stable vaterite includes vaterite that does nottransform to aragonite or calcite during and/or afterdissolution-re-precipitation process. The reactive vaterite or activatedvaterite includes vaterite that results in aragonite formation duringand/or after dissolution-re-precipitation process. In some embodiments,the PCC formed is in vaterite form. In some embodiments, the methodsdescribed herein further include contacting the precipitation material(in dried or wet form) with water and transforming the reactive vateriteto aragonite. In some embodiments, the stable vaterite when contactedwith water does not transform to aragonite and stays either in thevaterite form or transforms over a long period of time to calcite.

Typically, upon precipitation of the calcium carbonate, amorphouscalcium carbonate (ACC) may initially precipitate and transform into oneor more of its three more stable phases (vaterite, aragonite, orcalcite). A thermodynamic driving force may exist for the transformationfrom unstable phases to more stable phases. For this reason, calciumcarbonate phases transform in the order: ACC to vaterite, aragonite, andcalcite where intermediate phases may or may not be present. During thistransformation, excesses of energy are released, as exhibited by FIG. 8. This intrinsic energy may be harnessed to create a strong aggregationtendency and surface interactions that may lead to agglomeration andsetting or cementing. It is to be understood that the values reported inFIG. 8 are well known in the art and may vary.

The methods and systems provided herein produce or isolate theprecipitation material in the vaterite form or in the form of PCC whichmay be present in vaterite, aragonite, or calcite form. Theprecipitation material may be in a wet form, slurry form, or a drypowder form. This precipitation material may have a stable vaterite formthat does not transform readily to any other polymorph or may have areactive vaterite form that transforms to aragonite form upondissolution-re-precipitation. The aragonite form may not convert furtherto more stable calcite form. The product containing the aragonite formof the precipitate shows one or more unexpected properties, includingbut not limited to, high compressive strength, high porosity (lowdensity or light weight), neutral pH (useful as artificial reefdescribed below), microstructure network, etc.

Other minor polymorph forms of calcium carbonate that may be present inthe carbonate containing precipitation material in addition to vateriteinclude, but not limited to, amorphous calcium carbonate, aragonite,calcite, a precursor phase of vaterite, a precursor phase of aragonite,an intermediary phase that is less stable than calcite, polymorphicforms in between these polymorphs or combination thereof.

Vaterite may be present in monodisperse or agglomerated form, and may bein spherical, ellipsoidal, plate like shape, or hexagonal system.Vaterite typically has a hexagonal crystal structure and formspolycrystalline spherical particles upon growth. The precursor form ofvaterite comprises nanoclusters of vaterite and the precursor form ofaragonite comprises sub-micron to nanoclusters of aragonite needles.Aragonite, if present in the composition along with vaterite, may beneedle shaped, columnar, or crystals of the rhombic system. Calcite, ifpresent in the composition along with vaterite, may be cubic, spindle,or crystals of hexagonal system. An intermediary phase that is lessstable than calcite may be a phase that is between vaterite and calcite,a phase between precursor of vaterite and calcite, a phase betweenaragonite and calcite, and/or a phase between precursor of aragonite andcalcite.

The transformation between calcium carbonate polymorphs may occur viasolid-state transition, may be solution mediated, or both. In someembodiments, the transformation is solution-mediated as it may requireless energy than the thermally activated solid-state transition.Vaterite is metastable and the difference in thermodynamic stability ofcalcium carbonate polymorphs may be manifested as a difference insolubility, where the least stable phases are the most soluble.Therefore, vaterite may dissolve readily in solution and transformfavorably towards a more stable polymorph, such as aragonite. In apolymorphic system like calcium carbonate, two kinetic processes mayexist simultaneously in solution: dissolution of the metastable phaseand growth of the stable phase. In some embodiments, the aragonitecrystals may be growing while vaterite is undergoing dissolution in theaqueous medium.

In one aspect, the reactive vaterite may be activated such that thereactive vaterite leads to aragonitic pathway and not calcite pathwayduring dissolution-re-precipitation process. In some embodiments, thereactive vaterite containing composition is activated in such a way thatafter the dissolution-re-precipitation process, the aragonite formationis enhanced and the calcite formation is suppressed. The activation ofthe reactive vaterite containing composition may result in control overthe aragonite formation and crystal growth. The activation of thevaterite containing composition may be achieved by various processes.Various examples of the activation of vaterite, such as, but not limitedto, nuclei activation, thermal activation, mechanical activation,chemical activation, or combination thereof, are described herein. Insome embodiments, the vaterite is activated through various processessuch that aragonite formation and its morphology and/or crystal growthcan be controlled upon reaction of vaterite containing composition withwater. The aragonite formed results in higher tensile strength andfracture tolerance to the products formed from the reactive vaterite.

In some embodiments, the reactive vaterite may be activated bymechanical means, as described herein. For example, the reactivevaterite containing compositions may be activated by creating surfacedefects on the vaterite composition such that the aragonite formation isaccelerated. In some embodiments, the activated vaterite is aball-milled reactive vaterite or is a reactive vaterite with surfacedefects such that aragonite formation pathway is facilitated.

The reactive vaterite containing compositions may also be activated byproviding chemical or nuclei activation to the vaterite composition.Such chemical or nuclei activation may be provided by one or more ofaragonite seeds, inorganic additive, or organic additive. The aragoniteseed present in the compositions provided herein may be obtained fromnatural or synthetic sources. The natural sources include, but notlimited to, reef sand, lime, hard skeletal material of certainfresh-water and marine invertebrate organisms, including pelecypods,gastropods, mollusk shell, and calcareous endoskeleton of warm- andcold-water corals, pearls, rocks, sediments, ore minerals (e.g.,serpentine), and the like. The synthetic sources include, but notlimited to, precipitated aragonite, such as formed from sodium carbonateand calcium chloride; or aragonite formed by the transformation ofvaterite to aragonite, such as transformed vaterite described herein.

In some embodiments, the inorganic additive or the organic additive inthe compositions provided herein can be any additive that activatesreactive vaterite. Some examples of inorganic additive or organicadditive in the compositions provided herein, include, but not limitedto, sodium decyl sulfate, lauric acid, sodium salt of lauric acid, urea,citric acid, sodium salt of citric acid, phthalic acid, sodium salt ofphthalic acid, taurine, creatine, dextrose, poly(n-vinyl-1-pyrrolidone),aspartic acid, sodium salt of aspartic acid, magnesium chloride, aceticacid, sodium salt of acetic acid, glutamic acid, sodium salt of glutamicacid, strontium chloride, gypsum, lithium chloride, sodium chloride,glycine, sodium citrate dehydrate, sodium bicarbonate, magnesiumsulfate, magnesium acetate, sodium polystyrene, sodium dodecylsulfonate,poly-vinyl alcohol, or combination thereof. In some embodiments,inorganic additive or organic additive in the compositions providedherein, include, but not limited to, taurine, creatine,poly(n-vinyl-1-pyrrolidone), lauric acid, sodium salt of lauric acid,urea, magnesium chloride, acetic acid, sodium salt of acetic acid,strontium chloride, magnesium sulfate, magnesium acetate, or combinationthereof. In some embodiments, inorganic additive or organic additive inthe compositions provided herein, include, but not limited to, magnesiumchloride, magnesium sulfate, magnesium acetate, or combination thereof.

Without being limited by any theory, it is contemplated that theactivation of vaterite by ball-milling or by addition of aragonite seed,inorganic additive or organic additive or combination thereof may resultin control of formation of aragonite during dissolution-re-precipitationprocess of the activated reactive vaterite including control ofproperties, such as, but not limited to, polymorph, morphology, particlesize, cross-linking, agglomeration, coagulation, aggregation,sedimentation, crystallography, inhibiting growth along a certain faceof a crystal, allowing growth along a certain face of a crystal, orcombination thereof. For example, the aragonite seed, inorganic additiveor organic additive may selectively target the morphology of aragonite,inhibit calcite growth and promote the formation of aragonite that maygenerally not be favorable kinetically.

In some embodiments, one or more inorganic additives may be added tofacilitate transformation of vaterite to aragonite. The one or moreadditives may be added during any step of the process. For example, theone or more additives may be added during contact of the first aqueoussolution comprising calcium salt with carbon dioxide gas and optionallyammonia gas or the second aqueous solution; after contact of the firstaqueous solution comprising calcium salt with carbon dioxide gas andoptionally ammonia gas or the second aqueous solution; duringprecipitation of the precipitation material, after precipitation of theprecipitation material in the slurry, in the slurry after the dewateringof the precipitation material, in the powder after the drying of theslurry, in the aqueous solution to be mixed with the powderprecipitation material, or in the slurry made from the powderedprecipitation material with water, or any combination thereof. In someembodiments, the water used in the process of making the precipitationmaterial may already contain the one or more additives or the one ormore additive ions. For example, if sea water is used in the process,then the additive ion may already be present in the sea water.

In some embodiments, in the foregoing methods, the amount of the one ormore additives added during the process is more than 0.1% by weight, ormore than 0.5% by weight, or more than 1% by weight, or more than 1.5%by weight, or more than 1.6% by weight, or more than 1.7% by weight, ormore than 1.8% by weight, or more than 1.9% by weight, or more than 2%by weight, or more than 2.1% by weight, or more than 2.2% by weight, ormore than 2.3% by weight, or more than 2.4% by weight, or more than 2.5%by weight, or more than 2.6% by weight, or more than 2.7% by weight, ormore than 2.8% by weight, or more than 2.9% by weight, or more than 3%by weight, or more than 3.5% by weight, or more than 4% by weight, ormore than 4.5% by weight, or more than 5% by weight, or between 0.5-5%by weight, or between 0.5-4% by weight, or between 0.5-3% by weight, or0.5-2% by weight, or 0.5-1% by weight, or 1-3% by weight, or 1-2.5% byweight, or 1-2% by weight, or 1.5-2.5% by weight, or 2-3% by weight, or2.5-3% by weight, or 0.5% by weight, or 1% by weight, or 1.5% by weight,or 2% by weight, or 2.5% by weight, or 3% by weight, or 3.5% by weight,or 4% by weight, or 4.5% by weight, or 5% by weight. In someembodiments, in the foregoing methods, the amount of the one or moreadditives added during the process is between 0.5-3% by weight orbetween 1.5-2.5% by weight.

In some embodiments, the precipitation material is in a powder form. Insome embodiments, the precipitation material is in a dry powder form. Insome embodiments, the precipitation material is disordered or is not inan ordered array or is in the powdered form. In still some embodiments,the precipitation material is in a partially or wholly hydrated form. Instill some embodiments, the precipitation material is in saltwater orfresh water. In still some embodiments, the precipitation material is inwater containing sodium chloride. In still some embodiments, theprecipitation material is in water containing alkaline earth metal ions,such as, but are not limited to, calcium, magnesium, etc. In someembodiments, the precipitation material is non-medical or is not formedical procedures.

The products made from the compositions or the precipitation materialprovided herein show one or more properties, such as, high compressivestrength, high durability, high porosity (light weight), high flexuralstrength, and less maintenance costs. In some embodiments, thecompositions or the precipitation material comprising reactive vateriteupon combination with water, setting, and hardening, have a compressivestrength of at least 3 MPa (megapascal), or at least 7 MPa, or at least10 MPa or in some embodiments, between 3-30 MPa, or between 14-80 MPa or14-35 MPa.

In some embodiments of the foregoing aspects and embodiments, thecomposition or the precipitation material includes at least 10% w/wvaterite; or at least 20% w/w vaterite; or at least 30% w/w vaterite; orat least 40% w/w vaterite; or at least 50% w/w vaterite; or at least 60%w/w vaterite; or at least 70% w/w vaterite; or at least 80% w/wvaterite; or at least 90% w/w vaterite; or at least 95% w/w vaterite; orat least 99% w/w vaterite; or from 10% w/w to 99% w/w vaterite; or from10% w/w to 90% w/w vaterite; or from 10% w/w to 80% w/w vaterite; orfrom 10% w/w to 70% w/w vaterite; or from 10% w/w to 60% w/w vaterite;or from 10% w/w to 50% w/w vaterite; or from 10% w/w to 40% w/wvaterite; or from 10% w/w to 30% w/w vaterite; or from 10% w/w to 20%w/w vaterite; or from 20% w/w to 99% w/w vaterite; or from 20% w/w to95% w/w vaterite; or from 20% w/w to 90% w/w vaterite; or from 20% w/wto 75% w/w vaterite; or from 20% w/w to 50% w/w vaterite; or from 30%w/w to 99% w/w vaterite; or from 30% w/w to 95% w/w vaterite; or from30% w/w to 90% w/w vaterite; or from 30% w/w to 75% w/w vaterite; orfrom 30% w/w to 50% w/w vaterite; or from 40% w/w to 99% w/w vaterite;or from 40% w/w to 95% w/w vaterite; or from 40% w/w to 90% w/wvaterite; or from 40% w/w to 75% w/w vaterite; or from 50% w/w to 99%w/w vaterite; or from 50% w/w to 95% w/w vaterite; or from 50% w/w to90% w/w vaterite; or from 50% w/w to 75% w/w vaterite; or from 60% w/wto 99% w/w vaterite; or from 60% w/w to 95% w/w vaterite; or from 60%w/w to 90% w/w vaterite; or from 70% w/w to 99% w/w vaterite; or from70% w/w to 95% w/w vaterite; or from 70% w/w to 90% w/w vaterite; orfrom 80% w/w to 99% w/w vaterite; or from 80% w/w to 95% w/w vaterite;or from 80% w/w to 90% w/w vaterite; or from 90% w/w to 99% w/wvaterite; or 10% w/w vaterite; or 20% w/w vaterite; or 30% w/w vaterite;or 40% w/w vaterite; or 50% w/w vaterite; or 60% w/w vaterite; or 70%w/w vaterite; or 75% w/w vaterite; or 80% w/w vaterite; or 85% w/wvaterite; or 90% w/w vaterite; or 95% w/w vaterite; or 99% w/w vaterite.The vatreite may be stable vaterite or reactive vaterite or PCC.

In some embodiments of the foregoing aspects and the foregoingembodiments, the precipitation material comprising reactive vateriteafter combination with water, setting, and hardening (i.e.transformation to aragonite) or the stable vaterite mixed with cementand water and after setting and hardening, has a compressive strength ofat least 3 MPa; at least 7 MPa; at least 14 MPa; or at least 16 MPa; orat least 18 MPa; or at least 20 MPa; or at least 25 MPa; or at least 30MPa; or at least 35 MPa; or at least 40 MPa; or at least 45 MPa; or atleast 50 MPa; or at least 55 MPa; or at least 60 MPa; or at least 65MPa; or at least 70 MPa; or at least 75 MPa; or at least 80 MPa; or atleast 85 MPa; or at least 90 MPa; or at least 95 MPa; or at least 100MPa; or from 3-50 MPa; or from 3-25 MPa; or from 3-15 MPa; or from 3-10MPa; or from 14-25 MPa; or from 14-100 MPa; or from 14-80 MPa; or from14-75 MPa; or from 14-50 MPa; or from 14-25 MPa; or from 17-35 MPa; orfrom 17-25 MPa; or from 20-100 MPa; or from 20-75 MPa; or from 20-50MPa; or from 20-40 MPa; or from 30-90 MPa; or from 30-75 MPa; or from30-60 MPa; or from 40-90 MPa; or from 40-75 MPa; or from 50-90 MPa; orfrom 50-75 MPa; or from 60-90 MPa; or from 60-75 MPa; or from 70-90 MPa;or from 70-80 MPa; or from 70-75 MPa; or from 80-100 MPa; or from 90-100MPa; or from 90-95 MPa; or 14 MPa; or 3 MPa; or 7 MPa; or 16 MPa; or 18MPa; or 20 MPa; or 25 MPa; or 30 MPa; or 35 MPa; or 40 MPa; or 45 MPa.For example, in some embodiments of the foregoing aspects and theforegoing embodiments, the composition or the precipitation materialafter setting, and hardening has a compressive strength of 3 MPa to 25MPa; or 14 MPa to 40 MPa; or 17 MPa to 40 MPa; or 20 MPa to 40 MPa; or30 MPa to 40 MPa; or 35 MPa to 40 MPa. In some embodiments, thecompressive strengths described herein are the compressive strengthsafter 1 day, or 3 days, or 7 days, or 28 days, or 56 days, or longer.

In some embodiments, the precipitation material comprising vaterite(stable or reactive) or PCC is a particulate composition with an averageparticle size of 0.1-100 microns. The average particle size (or averageparticle diameter) may be determined using any conventional particlesize determination method, such as, but not limited to, multi-detectorlaser scattering or laser diffraction or sieving. In certainembodiments, unimodel or multimodal, e.g., bimodal or other,distributions are present. Bimodal distributions may allow the surfacearea to be minimized, thus allowing a lower liquids/solids mass ratiowhen composition is mixed with water yet providing smaller reactiveparticles for early reaction. In some embodiments, the composition orthe precipitation material comprising vaterite (stable or reactive) orPCC provided herein is a particulate composition with an averageparticle size of 0.1-1000 microns; or 0.1-500 microns; or 0.1-100microns; or 0.1-50 microns; or 0.1-20 microns; or 0.1-10 microns; or0.1-5 microns; or 1-50 microns; or 1-25 microns; or 1-20 microns; or1-10 microns; or 1-5 microns; or 5-70 microns; or 5-50 microns; or 5-20microns; or 5-10 microns; or 10-100 microns; or 10-50 microns; or 10-20microns; or 10-15 microns; or 15-50 microns; or 15-30 microns; or 15-20microns; or 20-50 microns; or 20-30 microns; or 30-50 microns; or 40-50microns; or 50-100 microns; or 50-60 microns; or 60-100 microns; or60-70 microns; or 70-100 microns; or 70-80 microns; or 80-100 microns;or 80-90 microns; or 0.1 microns; or 0.5 microns; or 1 microns; or 2microns; or 3 microns; or 4 microns; or 5 microns; or 8 microns; or 10microns; or 15 microns; or 20 microns; or 30 microns; or 40 microns; or50 microns; or 60 microns; or 70 microns; or 80 microns; or 100 microns.For example, in some embodiments, the composition or the precipitationmaterial comprising vaterite (stable or reactive) or PCC provided hereinis a particulate composition with an average particle size of 0.1-20micron; or 0.1-15 micron; or 0.1-10 micron; or 0.1-8 micron; or 0.1-5micron; or 1-25 micron; or 1-20 micron; or 1-15 micron; or 1-10 micron;or 1-5 micron; or 5-20 micron; or 5-10 micron. In some embodiments, thecomposition or the precipitation material comprising vaterite (stable orreactive) or PCC includes two or more, or three or more, or four ormore, or five or more, or ten or more, or 20 or more, or 3-20, or 4-10different sizes of the particles in the composition or the precipitationmaterial. For example, the composition or the precipitation material mayinclude two or more, or three or more, or between 3-20 particles rangingfrom 0.1-10 micron, 10-50 micron, 50-100 micron, 100-200 micron, 200-500micron, 500-1000 micron, and/or sub-micron sizes of the particles. Insome embodiments, the PCC in the precipitation material may have averageparticle size below 0.1 micron, such as between 0.001 micron to 1 micronor more. In some embodiments, the PCC may be in nanometer particle size.

In some embodiments, the composition or the precipitation materialcomprising vaterite (stable or reactive) or PCC may further include OPCor Portland cement clinker. The amount of Portland cement component mayvary and range from 10 to 95% w/w; or 10 to 90% w/w; or 10 to 80% w/w;or 10 to 70% w/w; or 10 to 60% w/w; or 10 to 50% w/w; or 10 to 40% w/w;or 10 to 30% w/w; or 10 to 20% w/w; or 20 to 90% w/w; or 20 to 80% w/w;or 20 to 70% w/w; or 20 to 60% w/w; or 20 to 50% w/w; or 20 to 40% w/w;or 20 to 30% w/w; or 30 to 90% w/w; or 30 to 80% w/w; or 30 to 70% w/w;or 30 to 60% w/w; or 30 to 50% w/w; or 30 to 40% w/w; or 40 to 90% w/w;or 40 to 80% w/w; or 40 to 70% w/w; or 40 to 60% w/w; or 40 to 50% w/w;or 50 to 90% w/w; or 50 to 80% w/w; or 50 to 70% w/w; or 50 to 60% w/w;or 60 to 90% w/w; or 60 to 80% w/w; or 60 to 70% w/w; or 70 to 90% w/w;or 70 to 80% w/w. For example, the composition or the precipitationmaterial comprising vaterite (stable or reactive) or PCC may include ablend of 75% OPC and 25% composition; or 80% OPC and 20% composition; or85% OPC and 15% composition; or 90% OPC and 10% composition; or 95% OPCand 5% composition.

In certain embodiments, the composition or the precipitation materialcomprising vaterite (stable or reactive) or PCC may further include anaggregate. Aggregate may be included in the composition or theprecipitation material to provide for mortars which include fineaggregate and concretes which also include coarse aggregate. The fineaggregates are materials that almost entirely pass through a Number 4sieve (ASTM C 125 and ASTM C 33), such as silica sand. The coarseaggregate are materials that are predominantly retained on a Number 4sieve (ASTM C 125 and ASTM C 33), such as silica, quartz, crushed roundmarble, glass spheres, granite, lime, calcite, feldspar, alluvial sands,sands or any other durable aggregate, and mixtures thereof. As such, theaggregate is used broadly to refer to a number of different types ofboth coarse and fine particulate material, including, but are notlimited to, sand, gravel, crushed stone, slag, and recycled concrete. Insome embodiments, the aggregate added to the precipitation material isthe activated aggregate which has been activated on the surface by theprecipitation material (this embodiment has been described earlierherein). The amount and nature of the aggregate may vary widely. In someembodiments, the amount of aggregate may range from 25 to 80%, such as40 to 70% and including 50 to 70% w/w of the total composition made upof both the composition and the aggregate.

In some embodiments, the composition or the precipitation materialcomprising reactive vaterite, as prepared by the methods describedabove, sets and hardens after treatment with the aqueous medium underone or more suitable conditions. The aqueous medium includes, but is notlimited to, fresh water optionally containing additives or brine. Insome embodiments, the one or more suitable conditions include, but arenot limited to, temperature, pressure, time period for setting, a ratioof the aqueous medium to the composition, and combination thereof. Thetemperature may be related to the temperature of the aqueous medium. Insome embodiments, the temperature is in a range of 0-110° C.; or 0-80°C.; or 0-60° C.; or 0-40° C.; or 25-100° C.; or 25-75° C.; or 25-50° C.;or 37-100° C.; or 37-60° C.; or 40-100° C.; or 40-60° C.; or 50-100° C.;or 50-80° C.; or 60- 100° C.; or 60-80° C.; or 80-100° C. In someembodiments, the pressure is atmospheric pressure or above atm.pressure. In some embodiments, the time period for setting the cementproduct is 30 min. to 48 hrs; or 30 min. to 24 hrs; or 30 min. to 12hrs; or 30 min. to 8 hrs; or 30 min. to 4 hrs; or 30 min. to 2 hrs; 2 to48 hrs; or 2 to 24 hrs; or 2 to 12 hrs; or 2 to 8 hrs; or 2 to 4 hrs; 5to 48 hrs; or 5 to 24 hrs; or 5 to 12 hrs; or 5 to 8 hrs; or 5 to 4 hrs;or 5 to 2 hrs; 10 to 48 hrs; or 10 to 24 hrs; or 24 to 48 hrs.

During the mixing of the composition or the precipitation material withthe aqueous medium, the precipitate may be subjected to high shearmixer. After mixing, the precipitate may be dewatered again and placedin pre-formed molds to make formed building materials or may be used tomake formed building materials using the processes well known in the artor as described herein. Alternatively, the precipitate may be mixed withwater and may be allowed to set. The precipitate may set over a periodof days and may be then placed in the oven for drying, e.g., at 40° C.,or from 40° C.-60° C., or from 40° C.-50° C., or from 40° C.-100° C., orfrom 50° C.-60° C., or from 50° C.-80° C., or from 50° C.-100° C., orfrom 60° C.-80° C., or from 60° C.-100° C. The precipitate may besubjected to curing at high temperature, such as, from 50° C.-60° C., orfrom 50° C.-80° C., or from 50° C.-100° C., or from 60° C.-80° C., orfrom 60° C.-100° C., or 60° C., or 80° C.-100° C., in high humidity,such as, in 30%, or 40%, or 50%, or 60% humidity.

The product produced by the methods described herein may be an aggregateor building material or a pre-cast material or a formed buildingmaterial. In some embodiments, the product produced by the methodsdescribed herein includes non-cementitous materials such as paper,paint, PVC etc. In some embodiments, the product produced by the methodsdescribed herein includes artificial reefs. These products have beendescribed herein.

In some embodiments, the precipitation material comprising vaterite(stable or reactive) or PCC in wet or dried form, may be mixed with oneor more admixtures to impart one or more properties to the productincluding, but not limited to, strength, flexural strength, compressivestrength, porosity, thermal conductivity, etc. The amount of admixturethat is employed may vary depending on the nature of the admixture. Insome embodiments, the amount of the one or more admixtures range from 1to 50% w/w, such as 1-30% w/w, or 1-25% w/w, or 1-20% w/w/, or 2 to 10%w/w. Examples of the admixtures include, but not limited to, setaccelerators, set retarders, air-entraining agents, foaming agents,defoamers, alkali-reactivity reducers, bonding admixtures, dispersants,coloring admixtures, corrosion inhibitors, damp-proofing admixtures, gasformers, permeability reducers, pumping aids, shrinkage compensationadmixtures, fungicidal admixtures, germicidal admixtures, insecticidaladmixtures, rheology modifying agents, finely divided mineraladmixtures, pozzolans, aggregates, wetting agents, strength enhancingagents, water repellents, reinforced material such as fibers, and anyother admixture. When using an admixture, the composition or theprecipitation material, to which the admixture raw materials areintroduced, is mixed for sufficient time to cause the admixture rawmaterials to be dispersed relatively uniformly throughout thecomposition.

Set accelerators may be used to accelerate the setting and earlystrength development of cement. Examples of set accelerators that may beused include, but are not limited to, POZZOLITH®NC534, non-chloride typeset accelerator and/or RHEOCRETE®CNI calcium nitrite-based corrosioninhibitor, both sold under the above trademarks by BASF Admixtures Inc.of Cleveland, Ohio. Set retarding, also known as delayed-setting orhydration control, admixtures are used to retard, delay, or slow therate of setting of cement. Most set retarders may also act as low levelwater reducers and can also be used to entrain some air into product. Anexample of a retarder is DELVO® by BASF Admixtures Inc. of Cleveland,Ohio. The air entrainer includes any substance that will entrain air inthe compositions. Some air entrainers can also reduce the surfacetension of a composition at low concentration. Air-entraining admixturesare used to purposely entrain microscopic air bubbles into cement. Airentrainment may increase the workability of the mix while eliminating orreducing segregation and bleeding. Materials used to achieve thesedesired effects can be selected from wood resin, natural resin,synthetic resin, sulfonated lignin, petroleum acids, proteinaceousmaterial, fatty acids, resinous acids, alkylbenzene sulfonates,sulfonated hydrocarbons, vinsol resin, anionic surfactants, cationicsurfactants, nonionic surfactants, natural rosin, synthetic rosin, aninorganic air entrainer, synthetic detergents, and their correspondingsalts, and mixtures thereof. Air entrainers are added in an amount toyield a desired level of air in a cementitious composition. Examples ofair entrainers that can be utilized in the admixture system include, butare not limited to MB AE 90, MB VR and MICRO AIR®, all available fromBASF Admixtures Inc. of Cleveland, Ohio.

In some embodiments, the precipitation material is mixed with foamingagent. The foaming agents incorporate large quantities of airvoids/porosity and facilitate reduction of the material's density.Examples of foaming agents include, but not limited to, soap, detergent(alkyl ether sulfate), Millifoam™ (alkyl ether sulfate), Cedepal™(ammonium alkyl ethoxy sulfate), Witcolate™ 12760, and the like.

Also of interest as admixtures are defoamers. Defoamers are used todecrease the air content in the cementitious composition. Also ofinterest as admixtures are dispersants. The dispersant includes, but isnot limited to, polycarboxylate dispersants, with or without polyetherunits. The term dispersant is also meant to include those chemicals thatalso function as a plasticizer, water reducer such as a high range waterreducer, fluidizer, antiflocculating agent, or superplasticizer forcompositions, such as lignosulfonates, salts of sulfonated naphthalenesulfonate condensates, salts of sulfonated melamine sulfonatecondensates, beta naphthalene sulfonates, sulfonated melamineformaldehyde condensates, naphthalene sulfonate formaldehyde condensateresins for example LOMAR D® dispersant (Cognis Inc., Cincinnati, Ohio),polyaspartates, or oligomeric dispersants. Polycarboxylate dispersantscan be used, by which is meant a dispersant having a carbon backbonewith pendant side chains, wherein at least a portion of the side chainsare attached to the backbone through a carboxyl group or an ether group.

Natural and synthetic admixtures may be used to color the product foraesthetic and safety reasons. These coloring admixtures may be composedof pigments and include carbon black, iron oxide, phthalocyanine, umber,chromium oxide, titanium oxide, cobalt blue, and organic coloringagents. Also of interest as admixtures are corrosion inhibitors.Corrosion inhibitors may serve to protect embedded reinforcing steelfrom corrosion. The materials commonly used to inhibit corrosion arecalcium nitrite, sodium nitrite, sodium benzoate, certain phosphates orfluorosilicates, fluoroaluminites, amines and related chemicals. Also ofinterest are damp-proofing admixtures. Damp-proofing admixtures reducethe permeability of the product that has low cement contents, highwater-cement ratios, or a deficiency of fines in the aggregate. Theseadmixtures retard moisture penetration into dry products and includecertain soaps, stearates, and petroleum products. Also of interest aregas former admixtures. Gas formers, or gas-forming agents, are sometimesadded to the mix to cause a slight expansion prior to hardening. Theamount of expansion is dependent upon the amount of gas-forming materialused and the temperature of the fresh mixture. Aluminum powder, resinsoap and vegetable or animal glue, saponin or hydrolyzed protein can beused as gas formers. Also of interest are permeability reducers.Permeability reducers may be used to reduce the rate at which waterunder pressure is transmitted through the mix. Silica fume, fly ash,ground slag, natural pozzolans, water reducers, and latex may beemployed to decrease the permeability of the mix.

Also of interest are rheology modifying agent admixtures. Rheologymodifying agents may be used to increase the viscosity of thecompositions. Suitable examples of rheology modifier include firmedsilica, colloidal silica, hydroxyethyl cellulose, starch, hydroxypropylcellulose, fly ash (as defined in ASTM C618), mineral oils (such aslight naphthenic), clay such as hectorite clay, polyoxyalkylenes,polysaccharides, natural gums, or mixtures thereof. Some of the mineralextenders such as, but not limited to, sepiolite clay are rheologymodifying agents.

Also of interest are shrinkage compensation admixtures. TETRAGUARD® isan example of a shrinkage reducing agent and is available from BASFAdmixtures Inc. of Cleveland, Ohio. Bacterial and fungal growth on or inhardened product may be partially controlled through the use offungicidal and germicidal admixtures. The materials for these purposesinclude, but are not limited to, polyhalogenated phenols, dialdrinemulsions, and copper compounds. Also of interest in some embodiments isworkability improving admixtures. Entrained air, which acts like alubricant, can be used as a workability improving agent. Otherworkability agents are water reducers and certain finely dividedadmixtures.

In some embodiments, the composition or the precipitation materialcomprising vaterite (stable or reactive) or PCC is employed withreinforced material such as fibers, e.g., where fiber-reinforced productis desirable. Fibers can be made of zirconia containing materials,aluminum, glass, steel, carbon, ceramic, grass, bamboo, wood,fiberglass, or synthetic materials, e.g., polypropylene, polycarbonate,polyvinyl chloride, polyvinyl alcohol, nylon, polyethylene, polyester,rayon, high-strength aramid, (i.e. Kevlar®), or mixtures thereof. Thereinforced material is described in U.S. patent application Ser. No.13/560,246, filed Jul. 27, 2012, which is incorporated herein in itsentirety in the present disclosure.

The components of the precipitation material comprising vaterite (stableor reactive) or PCC can be combined using any suitable protocol. Eachmaterial may be mixed at the time of work, or part of or all of thematerials may be mixed in advance. Alternatively, some of the materialsare mixed with water with or without admixtures, such as high-rangewater-reducing admixtures, and then the remaining materials may be mixedtherewith. As a mixing apparatus, any conventional apparatus can beused. For example, Hobart mixer, slant cylinder mixer, Omni Mixer,Henschel mixer, V-type mixer, and Nauta mixer can be employed.

In one aspect, there are provided systems to form calcium carbonatecomprising vaterite, comprising (i) a dissolution reactor configured fordissolving lime in an aqueous base solution under one or moreprecipitation conditions to produce a precipitation material comprisingcalcium carbonate and a supernatant solution, wherein the calciumcarbonate comprises vaterite.

In one aspect, there are provided systems to form calcium carbonatecomprising vaterite, comprising (i) a calcination reactor configured forcalcining limestone to form lime and a gaseous stream of carbon dioxide;(ii) a dissolution reactor configured for dissolving the lime in anaqueous base solution under one or more dissolution conditions toproduce a first aqueous solution comprising calcium salt, and a gaseousstream comprising ammonia; and (iii) a treatment reactor configured fortreating the first aqueous solution comprising calcium salt with thegaseous stream comprising carbon dioxide and the gaseous streamcomprising ammonia under one or more precipitation conditions to form aprecipitation material comprising calcium carbonate and a supernatantsolution, wherein the calcium carbonate comprises vaterite.

In one aspect, there are provided systems to form calcium carbonatecomprising vaterite, comprising (i) a calcination reactor configured forcalcining limestone to lime and a gaseous stream of carbon dioxide; (ii)a dissolution reactor configured for dissolving the lime in an aqueousN-containing inorganic salt solution under one or more dissolutionconditions to produce a first aqueous solution comprising calcium salt,and a gaseous stream comprising ammonia; and (iii) a treatment reactorconfigured for treating the first aqueous solution comprising calciumsalt with the gaseous stream comprising carbon dioxide and the gaseousstream comprising ammonia under one or more precipitation conditions toform a precipitation material comprising calcium carbonate and asupernatant solution, wherein the calcium carbonate comprises vaterite.

In one aspect, there are provided systems to form calcium carbonatecomprising vaterite, comprising (i) a calcination reactor configured forcalcining limestone to lime and a gaseous stream of carbon dioxide; (ii)a dissolution reactor configured for dissolving the lime in an aqueousN-containing inorganic salt solution under one or more dissolutionconditions to produce a first aqueous solution comprising calcium salt,and a gaseous stream comprising ammonia; (iii) a cooling reactorconfigured for recovering the gaseous stream comprising carbon dioxideand the gaseous stream comprising ammonia and subjecting the gaseousstream to a cooling process under one or more cooling conditions tocondense a second aqueous solution comprising ammonium bicarbonate,ammonium carbonate, ammonia, ammonia carbamate, or combinations thereof;and (iv) a treatment reactor configured for treating the first aqueoussolution comprising calcium salt with the second aqueous solutioncomprising ammonium bicarbonate, ammonium carbonate, ammonia, ammoniumcarbamate or combinations thereof under one or more precipitationconditions to form a precipitation material comprising calcium carbonateand a supernatant solution, wherein the calcium carbonate comprisesvaterite. In some embodiments of the aforementioned aspect, the vateriteis stable vaterite, reactive vaterite or PCC. In some embodiments of theaforementioned aspect and embodiments, the dissolution reactor isintegrated with the cooling reactor (as illustrated in FIGS. 4-7 anddescribed herein).

In some embodiments of the aforementioned aspects and embodiments, thesystem further comprises a recovering system to recover the base fromthe aqueous solution to be recycled back to the dissolution reactor. Therecovering system is the system configured to carry out thermaldecomposition, reverse osmosis, multi-stage flash, multi-effectdistillation, vapor recompression, distillation, and combinationsthereof, as described herein above.

The methods and systems provided herein may be carried out at land(e.g., at a location close to the limestone quarry, or is easily andeconomically transported in), at sea, or in the ocean. In someembodiments, the cement plants calcining the lime may be retro-fittedwith the systems described herein to form the precipitation material andfurther to form products from the precipitation material.

Aspects include systems, including processing plants or factories, forpracticing the methods as described herein. Systems may have anyconfiguration that enables practice of the particular production methodof interest.

In certain embodiments, the systems include a source of lime and astructure having an input for the aqueous base solution. For example,the systems may include a pipeline or analogous feed of aqueous basesolution, wherein the aqueous base solution is as described herein. Thesystem further includes an input for CO₂ as well as components forcombining these sources with water (optionally an aqueous solution suchas water, brine or seawater) before the precipitation reactor or in theprecipitation reactor. In some embodiments, the gas-liquid contactor isconfigured to contact enough CO₂ to produce the precipitation materialin excess of 1, 10, 100, 1,000, or 10,000 tons per day.

The systems further include a precipitation reactor that subjects thewater introduced to the precipitation reactor to the one or moreprecipitation conditions (as described herein) and producesprecipitation material and supernatant. In some embodiments, theprecipitation reactor is configured to hold water sufficient to producethe precipitation material in excess of 1, 10, 100, 1,000, or 10,000tons per day. The precipitation reactor may also be configured toinclude any of a number of different elements such as temperaturemodulation elements (e.g., configured to heat the water to a desiredtemperature), chemical additive elements (e.g., configured forintroducing additives etc. into the precipitation reaction mixture),computer automation, and the like.

The gaseous waste stream comprising CO₂ and optionally NH₃ may beprovided to the precipitation reactor and/or the cooling reactor in anyconvenient manner. In some embodiments, the gaseous waste stream isprovided with a gas conveyer (e.g., a duct) that runs from thedissolution reactor to the precipitation reactor and/or the coolingreactor.

Where the water source that is processed by the system to produce theprecipitation material is seawater, the input is in fluid communicationwith a source of sea water, e.g., such as where the input is a pipelineor feed from ocean water to a land based system or a inlet port in thehull of ship, e.g., where the system is part of a ship, e.g., in anocean based system.

The methods and systems may also include one or more detectorsconfigured for monitoring the aqueous base solution, the lime, and/orthe carbon dioxide (not illustrated in figures). Monitoring may include,but is not limited to, collecting data about the pressure, temperatureand composition of the water or the carbon dioxide gas. The detectorsmay be any convenient device configured to monitor, for example,pressure sensors (e.g., electromagnetic pressure sensors, potentiometricpressure sensors, etc.), temperature sensors (resistance temperaturedetectors, thermocouples, gas thermometers, thermistors, pyrometers,infrared radiation sensors, etc.), volume sensors (e.g., geophysicaldiffraction tomography, X-ray tomography, hydroacoustic surveyers,etc.), and devices for determining chemical makeup of the water or thecarbon dioxide gas (e.g, IR spectrometer, NMR spectrometer, UV-visspectrophotometer, high performance liquid chromatographs, inductivelycoupled plasma emission spectrometers, inductively coupled plasma massspectrometers, ion chromatographs, X-ray diffractometers, gaschromatographs, gas chromatography-mass spectrometers, flow-injectionanalysis, scintillation counters, acidimetric titration, and flameemission spectrometers, etc.).

In some embodiments, detectors may also include a computer interfacewhich is configured to provide a user with the collected data about theaqueous base solution, the lime, and/or the carbon dioxide/ammonia gas.In some embodiments, the summary may be stored as a computer readabledata file or may be printed out as a user readable document.

In some embodiments, the detector may be a monitoring device such thatit can collect real-time data (e.g., internal pressure, temperature,etc.). In other embodiments, the detector may be one or more detectorsconfigured to determine the parameters of the aqueous base solution, thelime, and/or the carbon dioxide gas at regular intervals, e.g.,determining the composition every 1 minute, every 5 minutes, every 10minutes, every 30 minutes, every 60 minutes, every 100 minutes, every200 minutes, every 500 minutes, or some other interval.

In certain embodiments, the system may further include a station forpreparing a building material, such as cement or aggregate, from theprecipitate. Other materials such as formed building materials and/ornon-cementitious materials may also be formed from the precipitate andappropriate station may be used for preparing the same.

As indicated above, the system may be present on land or sea. Forexample, the system may be land-based system that is in a coastalregion, e.g., close to a source of seawater, or even an interiorlocation, where water is piped into the system from a water source,e.g., ocean. Alternatively, the system is a water based system, i.e., asystem that is present on or in water. Such a system may be present on aboat, ocean based platform etc., as desired.

Calcium carbonate slurry is pumped via pump to drying system, which insome embodiments includes a filtration step followed by spray drying.The water separated from the drying system is discharged or isrecirculated to the reactor. The resultant solid or powder from thedrying system is utilized as cement or aggregate to produce buildingmaterials. The solid or powder may also be used as a PCC filler innon-cementitious products such as paper, plastic, paint etc. The solidor powder may also be used in forming formed building materials, such asdrywall, cement boards, etc.

In some embodiments, the systems may include a control station,configured to control the amount of the aqueous base solution and/or theamount of the lime conveyed to the precipitator or the dissolutionreactor; the amount of the precipitate conveyed to the separator; theamount of the precipitate conveyed to the drying station; and/or theamount of the precipitate conveyed to the refining station. A controlstation may include a set of valves or multi-valve systems which aremanually, mechanically or digitally controlled, or may employ any otherconvenient flow regulator protocol. In some instances, the controlstation may include a computer interface, (where regulation iscomputer-assisted or is entirely controlled by computer) configured toprovide a user with input and output parameters to control the amount,as described above.

II. Products

Provided herein are methods and systems for utilizing the lime formedfrom the calcination of the limestone by dissolving the lime in theaqueous base solution to produce the precipitation material comprisingcalcium carbonate in vaterite and/or aragonite polymorphic forms whichvaterite transforms to aragonite and forms cement. Provided herein areenvironmentally friendly methods and systems of removing or separatingCO₂ in a gaseous waste stream from the calcination of the limestone, andfixing the CO₂ into a non-gaseous, storage-stable form (e.g., materialsfor the construction of structures such as buildings and infrastructure,as well as the structures themselves or formed building materials suchas drywall, or non-cementitious materials such as paper, paint, plastic,etc. or artificial reefs) such that the CO₂ does not escape into theatmosphere.

Building Material

The “building material” used herein includes material used inconstruction. In one aspect, there is provided a structure or a buildingmaterial comprising the set and hardened form of the precipitationmaterial e.g. where the reactive vaterite has converted to aragonite orPCC that sets and hardens. The product (product (A) or (B) in thefigures) containing the aragonite form of the precipitate (aragoniteformed by the dissolution-re-precipitation of the reactive vaterite)shows one or more unexpected properties, including but not limited to,high compressive strength, high porosity (low density or light weight),neutral pH (e.g. useful as artificial reef), microstructure network,etc.

Examples of such structures or the building materials include, but arenot limited to, building, driveway, foundation, kitchen slab, furniture,pavement, road, bridges, motorway, overpass, parking structure, brick,block, wall, footing for a gate, fence, or pole, and combinationthereof.

Formed Building Material

The “formed building material” used herein includes materials shaped(e.g., molded, cast, cut, or otherwise produced) into structures withdefined physical shape. The formed building material may be a pre-castbuilding material, such as, a pre-cast cement or concrete product. Theformed building materials and the methods of making and using the formedbuilding materials are described in U.S. application Ser. No.12/571,398, filed Sep. 30, 2009, which is incorporated herein byreference in its entirety. The formed building materials may varygreatly and include materials shaped (e.g., molded, cast, cut, orotherwise produced) into structures with defined physical shape, i.e.,configuration. Formed building materials are distinct from amorphousbuilding materials (e.g., powder, paste, slurry, etc.) that do not havea defined and stable shape, but instead conform to the container inwhich they are held, e.g., a bag or other container. Formed buildingmaterials are also distinct from irregularly or imprecisely formedmaterials (e.g., aggregate, bulk forms for disposal, etc.) in thatformed building materials are produced according to specifications thatallow for use of formed building materials in, for example, buildings.Formed building materials may be prepared in accordance with traditionalmanufacturing protocols for such structures, with the exception that theprecipitation material is employed in making such materials.

In some embodiments, the methods and systems provided herein furtherinclude setting and hardening the precipitation material comprisingreactive vaterite where the reactive vaterite has converted toaragonite, or the PCC that has set and hardened and forming a formedbuilding material.

In some embodiments, the formed building materials made from theprecipitation material have a compressive strength or the flexuralstrength of at least 3 MPa, at least 10 MPa, or at least 14 MPa, orbetween 3-30 MPa, or between about 14-100 MPa, or between about 14-45MPa; or the compressive strength of the precipitation material aftersetting, and hardening, as described herein.

Examples of the formed building materials that can be produced by theforegoing methods and systems, include, but not limited to, masonryunits, for example only, bricks, blocks, and tiles including, but notlimited to, ceiling tiles; construction panels, for example only, cementboard (boards traditionally made from cement such as fiber cement board)and/or drywall (boards traditionally made from gypsum); conduits;basins; beam; column, slab; acoustic barrier; insulation material; orcombinations thereof. Construction panels are formed building materialsemployed in a broad sense to refer to any non-load-bearing structuralelement that are characterized such that their length and width aresubstantially greater than their thickness. As such the panel may be aplank, a board, shingles, and/or tiles. Exemplary construction panelsformed from the precipitation material provided herein include cementboards and/or drywall. Construction panels are polygonal structures withdimensions that vary greatly depending on their intended use. Thedimensions of construction panels may range from 50 to 500 cm in length,including 100 to 300 cm, such as 250 cm; width ranging from 25 to 200cm, including 75 to 150 cm, such as 100 cm; thickness ranging from 5 to25 mm, including 7 to 20 mm, including 10 to 15 mm.

In some embodiments, the cement board and/or the drywall may be used inmaking different types of boards such as, but not limited to,paper-faced board (e.g. surface reinforcement with cellulose fiber),fiberglass-faced or glass mat-faced board (e.g. surface reinforcementwith glass fiber mat), fiberglass mesh reinforced board (e.g. surfacereinforcement with glass mesh), and/or fiber-reinforced board (e.g.cement reinforcement with cellulose, glass, fiber etc.). These boardsmay be used in various applications including, but not limited to,sidings such as, fiber-cement sidings, roofing, soffit, sheathing,cladding, decking, ceiling, shaft liner, wall board, backer, trim,frieze, shingle, and fascia, and/or underlayment.

The cement boards traditionally are made from cement such as OPC,magnesium oxide cement and/or calcium silicate cement. The cement boardsmade by the methods and systems provided herein are made from theprecipitation material that partially or wholly replaces the traditionalcement in the board. In some embodiments, the cement boards may compriseconstruction panels prepared as a combination of aragonitic cement(setting and hardening when vaterite transforms to aragonite) and fiberand/or fiberglass and may possess additional fiber and/or fiberglassreinforcement at both faces of the board.

The cement boards are formed building materials which in someembodiments, are used as backer boards for ceramics that may be employedbehind bathroom tiles, kitchen counters, backsplashes, etc. and may havelengths ranging from 100 to 200 cm. Cement boards may vary in physicaland mechanical properties. In some embodiments, the flexural strengthmay vary, ranging between 1 to 7.5 MPa, including 2 to 6 MPa, such as 5MPa. The compressive strengths may also vary, ranging from 5 to 50 MPa,including 10 to 30 MPa, such as 15 to 20 MPa. In some embodiments,cement boards may be employed in environments having extensive exposureto moisture (e.g., commercial saunas). The composition or theprecipitation material described herein may be used to produce thedesired shape and size to form a cement board. In addition, a variety offurther components may be added to the cement boards which include, butare not limited to, plasticizers, clay, foaming agents, accelerators,retarders and air entrainment additives. The composition is then pouredout into sheet molds or a roller may be used to form sheets of a desiredthickness. The shaped composition may be further compacted by rollercompaction, hydraulic pressure, vibrational compaction, or resonantshock compaction. The sheets are then cut to the desired dimensions ofthe cement boards.

Another type of construction panel formed from the composition or theprecipitation material described herein is backer board. The backerboard may be used for the construction of interior, and/or exteriorfloors, walls and ceilings. In the embodiments, the backer board is madepartially or wholly from the precipitation material.

Another type of construction panel formed from the compositions or theprecipitation material is drywall. The drywall includes board that isused for construction of interior, and/or exterior floors, walls andceilings. Traditionally, drywall is made from gypsum (called paper-facedboard). In the embodiments, the drywall is made partially or wholly fromthe carbonate precipitation material thereby replacing gypsum from thedrywall product. In some embodiments, the drywall may compriseconstruction panels prepared as a combination of aragonitic cement(setting and hardening when vaterite transforms to aragonite) andcellulose, fiber and/or fiberglass and may possess additional paper,fiber, fiberglass mesh and/or fiberglass mat reinforcement at both facesof the board. Various processes for making the drywall product are wellknown in the art and are well within the scope of the invention. Someexamples include, but not limited to, wet process, semi dry process,extrusion process, Wonderborad® process, etc., that have been describedherein.

In some embodiments, the drywall is panel made of a paper liner wrappedaround an inner core. For example, in some embodiments, during theprocess of making the drywall product from the precipitation material,the slurry of the precipitation material comprising vaterite is pouredover a sheet of paper. Another sheet of paper is then put on top of theprecipitation material such that the precipitation material is flankedby the paper on both sides (the resultant composition sandwiched betweentwo sheets of outer material, e.g., heavy paper or fiberglass mats). Thevaterite in the precipitation material is then transformed to aragonite(using additives and/or heat) which then sets and hardens. When the coresets and is dried in a large drying chamber, the sandwich becomes rigidand strong enough for use as a building material. The drywall sheets arethen cut and separated.

The flexural and compressive strengths of the drywall formed from theprecipitation material are equal to or higher than conventional drywallprepared with gypsum plaster, which is known to be a soft constructionmaterial. In some embodiments, the flexural strength may range between0.1 to 3 MPa, including 0.5 to 2 MPa, such as 1.5 MPa. The compressivestrengths may also vary, in some instances ranging from 1 to 20 MPa,including 5 to 15 MPa, such as 8 to 10 MPa. In some embodiments, theformed building materials such as, the construction panels such as, butnot limited to, cement boards and drywall produced by the methods andsystems described herein, have low density and high porosity making themsuitable for lightweight and insulation applications. The high porosityand light weight of the formed building materials such as constructionpanels may be due to the development of the aragonitic microstructurewhen vaterite transforms to aragonite. The transformation of thevaterite during dissolution/re-precipitation process may lead to microporosity generation while at the same time the voids created between thearagonitic crystals formed may provide nano porosity thereby leading tohighly porous and light weight structure. Certain admixtures may beadded during the transformation process such as, but not limited to,foaming agents, rheology modifiers and mineral extenders, such as, butnot limited to, clay, starch, etc. which may add to the porosity in theproduct as the foaming agent may entrain air in the mixture and lowerthe overall density and mineral extender such as sepiolite clay mayincrease the viscosity of the mixture thereby preventing segregation ofthe precipitation material and water.

One of the applications of the cement board or drywall is fiber cementsiding. Fiber-cement sidings formed by the methods and systems providedherein comprise construction panels prepared as a combination ofaragonitic cement, aggregate, interwoven cellulose, and/or polymericfibers and may possess a texture and flexibility that resembles wood.

In some embodiments, the formed building materials are masonry units.Masonry units are formed building materials used in the construction ofload-bearing and non-load-bearing structures that are generallyassembled using mortar, grout, and the like. Exemplary masonry unitsformed from the compositions include bricks, blocks, and tiles.

Another formed building material formed from the precipitation materialdescribed herein is a conduit. Conduits are tubes or analogousstructures configured to convey a gas or liquid, from one location toanother. Conduits can include any of a number of different structuresused in the conveyance of a liquid or gas that include, but are notlimited to, pipes, culverts, box culverts, drainage channels andportals, inlet structures, intake towers, gate wells, outlet structures,and the like.

Another formed building material formed from the precipitation materialdescribed herein is basins. The term basin may include any configuredcontainer used to hold a liquid, such as water. As such, a basin mayinclude, but is not limited to structures such as wells, collectionboxes, sanitary manholes, septic tanks, catch basins, greasetraps/separators, storm drain collection reservoirs, etc.

Another formed building material formed from the precipitation materialdescribed herein is a beam, which, in a broad sense, refers to ahorizontal load-bearing structure possessing large flexural andcompressive strengths. Beams may be rectangular cross-shaped, C-channel,L-section edge beams, I-beams, spandrel beams, H-beams, possess aninverted T-design, etc. Beams may also be horizontal load-bearing units,which include, but are not limited to joists, lintels, archways andcantilevers.

Another formed building material formed from the precipitation materialdescribed herein is a column, which, in a broad sense, refers to avertical load-bearing structure that carries loads chiefly through axialcompression and includes structural elements such as compressionmembers. Other vertical compression members of the invention mayinclude, but are not limited to pillars, piers, pedestals, or posts.

Another formed building material formed from the precipitation materialdescribed herein is a concrete slab. Concrete slabs are those buildingmaterials used in the construction of prefabricated foundations, floorsand wall panels. In some instances, a concrete slab may be employed as afloor unit (e.g., hollow plank unit or double tee design).

Another formed building material formed from the precipitation materialdescribed herein is an acoustic barrier, which refers to a structureused as a barrier for the attenuation or absorption of sound. As such,an acoustic barrier may include, but is not limited to, structures suchas acoustical panels, reflective barriers, absorptive barriers, reactivebarriers, etc.

Another formed building material formed from the precipitation materialdescribed herein is an insulation material, which refers to a materialused to attenuate or inhibit the conduction of heat. Insulation may alsoinclude those materials that reduce or inhibit radiant transmission ofheat.

In some embodiments, the other formed building materials such aspre-cast concrete products include, but not limited to, bunker silo;cattle feed bunk; cattle grid; agricultural fencing; H-bunks; J-bunks;livestock slats; livestock watering troughs; architectural panel walls;cladding (brick); building trim; foundation; floors, including slab ongrade; walls; double wall precast sandwich panel; aqueducts;mechanically stabilized earth panels; box culverts; 3-sided culverts;bridge systems; RR crossings; RR ties; sound walls/barriers; Jerseybarriers; tunnel segments; reinforced concrete box; utillity protectionstructure; hand holes; hollowcore product; light pole base; meter box;panel vault; pull box; telecom structure; transformer pad; transformervault; trench; utility vault; utility pole; controlled environmentvaults; underground vault; mausoleum; grave stone; coffin; haz matstorage container; detention vaults; catch basins; manholes; aerationsystem; distribution box; dosing tank; dry well; grease interceptor;leaching pit; sand-oil/oil-water interceptor; septic tank; water/sewagestorage tank; wetwells; fire cisterns; floating dock; underwaterinfrastructure; decking; railing; sea walls; roofing tiles; pavers;community retaining wall; res. retaining wall; modular block systems;and segmental retaining walls.

Non-Cementitious Compositions

In some embodiments, the methods and systems described herein includemaking other products from the precipitation material described hereinincluding, but not limited to, non-cementitious compositions includingpaper, polymer product, lubricant, adhesive, rubber product, chalk,asphalt product, paint, abrasive for paint removal, personal careproduct, cosmetic, cleaning product, personal hygiene product,ingestible product, agricultural product, soil amendment product,pesticide, environmental remediation product, and combination thereof.Such compositions have been described in U.S. Pat. No. 7,829,053, issuedNov. 9, 2010, which is incorporated herein by reference in its entirety.

Artificial Marine Structures

In some embodiments, the methods described herein include makingartificial marine structures from the precipitation material describedherein including, but not limited to, artificial corals and reefs. Insome embodiments, the artificial structures can be used in the aquariumsor sea. In some embodiments, these products are made from theprecipitated material comprising reactive vaterite that transforms toaragonite after setting and hardening. The aragonitic cement providesneutral or close to neutral pH which may be conducive for maintenanceand growth of marine life. The aragonitic reefs may provide suitablehabitat for marine species.

The following examples are put forth so as to provide those of ordinaryskill in the art with a complete disclosure and description of how tomake and use the invention, and are not intended to limit the scope ofwhat the inventors regard as their invention nor are they intended torepresent that the experiments below are all or the only experimentsperformed. Efforts have been made to ensure accuracy with respect tonumbers used (e.g. amounts, temperature, etc.) but some experimentalerrors and deviations should be accounted for.

EXAMPLES Example 1 Formation and Transformation of the PrecipitationMaterial from Lime

NH₄Cl is dissolved into water. Lime is added to the aqueous solution andmixed at 80° C. in a vessel with a vapor outlet tube. Vapor leaves thevessel through the outlet tube and is condensed along with CO₂ at 20° C.to form an aqueous solution containing ammonia, ammonium bicarbonate,and ammonium carbonate in a first airtight and collapsible bag. Thesolid and liquid mixture remaining in the vessel is cooled to 20° C. andvacuum filtered to remove the insoluble impurities. The clearCaCl₂-containing filtrate is transferred to a second airtight andcollapsible bag. Both bags are submersed in a water bath, which preheatsthe solutions to 35° C. The precipitation reactor is an acrylic cylinderequipped with baffles, pH electrode, thermocouple, turbine impeller, andinlet and outlet ports for liquid feeds and product slurry. Duringstartup, the CaCl₂-containing solution in the second bag is pumped intothe reactor at a fixed flow rate. The mixer is stirred while thesolution in the first bag is introduced by a separate pump. A computerautomated control loop controls the continuous inlet flow of theammonium carbonate-containing solution from the first bag maintainingthe pH between 7-9. Reactive vaterite slurry is formed. The resultantreactive vaterite slurry is continuously collected into a holdingcontainer. The slurry is vacuum filtered. The reactive vaterite filtercake is oven dried at 100° C. The cake shows 100% vaterite with a meanparticle size of 5 microns. The clear filtrate containing regeneratedNH₄Cl is recycled in subsequent experiments.

The dried reactive vaterite solid is mixed with water into a paste. TheXRD of the paste after 1 day shows 99.9% aragonite (vaterite fullyconverted to aragonite). The pastes are cast into 2″×2″×2″ cubes, whichset and harden in a humidity chamber set to 60° C. and 80% of relativehumidity for 7 days. The cemented cubes are dried in a 100° C. oven.Destructive testing determines the compressive strength of the cubes tobe 4600 psi (˜31 MPa).

Example 2 Formation and Transformation of the Precipitation Materialfrom Lime

NH₄Cl is dissolved into water. Lime is added to the aqueous solution andmixed under pressure at 120° C. in a dissolution vessel with outlets forvapor and slurry. Slurry containing insoluble impurities leaves throughthe bottom outlet and passes through a filter to remove solids. Theclear CaCl₂-containing filtrate is cooled to 30° C. and pumped to aprecipitation reactor. The precipitation reactor is an acrylic cylinderequipped with baffles, gas sparger, pH electrode, thermocouple, turbineimpeller, and inlet and outlet ports for liquid and gas feeds andproduct slurry. Vapor containing ammonia passes from the dissolutionreactor into a sparger located in the precipitation reactor. CO₂ is alsopassed into the precipitation reactor. A computer automated control loopcontrols the continuous inlet flow of the CaCl₂-containing solutionmaintaining the pH between 7-9. The resultant reactive vaterite slurryis continuously collected into a holding container. The slurry is vacuumfiltered. The reactive vaterite filter cake is oven dried at 100° C. Thecake shows 100% vaterite with a mean particle size of 5 microns. Theclear filtrate containing regenerated NH₄Cl is recycled in subsequentexperiments.

The dried reactive vaterite solid is mixed into a paste using water. TheXRD of the paste after 1 day shows 99.9% aragonite (vaterite fullyconverted to aragonite). The pastes are cast into 2″×2″×2″ cubes, whichset and harden in a humidity chamber set to 60° C. and 80% of relativehumidity for 7 days. The cemented cubes are dried in a 100° C. oven.Destructive testing determines the compressive strength of the cubes tobe 4600 psi (˜31 MPa).

Example 3 Control of the Formation of Products in the Cooling Reactor

NH₄Cl is dissolved into water. Lime is added to the aqueous solution andmixed at 80° C. in a vessel with a vapor outlet tube. Vapor comprisingammonia leaves the vessel through the outlet tube and is condensed alongwith CO₂ (and water vapor) at 20° C. to form an aqueous solutioncontaining ammonia, ammonium bicarbonate, ammonium carbonate, andammonium carbamate in a first airtight and collapsible bag. Theformation of the condensed products can be controlled by controlling theflow of CO₂ based on the pH of the aqueous solution.

A simulation of this process demonstrated that: (i) by varying CO₂ flowuntil an outlet pH of 10.3 was obtained, a stream was obtained withcarbamate:carbonate:bicarbonate ratio of 45%:35%:20%; (ii) by varyingCO₂ flow until an outlet pH of 9.7 was obtained, a stream was obtainedwith carbamate:carbonate:bicarbonate ratio of 35%:25%:40%; and (iii) byvarying CO₂ flow until an outlet pH of 8.7 was obtained, a stream wasobtained with carbamate:carbonate:bicarbonate ratio of 20%:10%:70%.

Therefore, as the pH of the system was reduced by regulating the flowrate of the CO₂, the amount of the bicarbonate was favored over thecarbamate and as the pH of the system was increased by regulating theflow rate of the CO₂, the amount of the carbamate was favored over thebicarbonate and the carbonate.

Example 4 Control of the Formation of Products in the Cooling Reactor

NH₄Cl is dissolved into water. Lime is added to the aqueous solution andmixed at 80° C. in a vessel with a vapor outlet tube. Vapor comprisingammonia leaves the vessel through the outlet tube and is condensed alongwith CO₂ (and water vapor) at 20° C. to form an aqueous solutioncontaining ammonia, ammonium bicarbonate, ammonium carbonate, andammonium carbamate in a first airtight and collapsible bag. Theformation of the condensed products can be controlled by controlling theratio of the CO₂:NH₃.

A simulation of this process demonstrated that: (i) by selecting flow ofCO₂ to be in a mass ratio of 0.2:1 CO₂:NH₃, the speciation was driven togreater than 98% carbonate; (ii) by selecting flow of CO₂ to be in amass ratio of 1:1 CO₂:NH₃, the speciation was driven to give greaterthan 15.6% carbamate; and (iii) by selecting flow of CO₂ to be in a massratio of 20:1 CO₂:NH₃, the speciation was driven to greater than 90%bicarbonate. The data is shown in Table I below as well as in FIG. 9 .The data demonstrated that the ratio of CO₂:NH₃ directly affected theratio of the products formed in the cooling reactor.

TABLE I CO₂:NH₃ 0.1 0.2 0.5 1 2 5 10 20 NH₃:NH₄ ⁺ 11.84 5.49 1.99 0.980.64 0.34 0.19 0.09 % CO₃ ⁻ 99.8% 98.9% 69.1% 23.5% 14.1%  7.6%  4.7% 3.0% (carbonate) % HCO₃ ⁻  0.1%  0.4% 20.4% 60.9% 70.7% 79.7% 85.4%90.2% (bicarbonate) % NH₂COO⁻  0.1%  0.7% 10.5% 15.6% 15.2% 12.7% 9.8% 6.8% (carbamate)

Although the foregoing invention has been described in some detail byway of illustration and example for purposes of clarity ofunderstanding, it should be readily apparent to those of ordinary skillin the art in light of the teachings of this invention that certainchanges and modifications may be made thereto without departing from thespirit or scope of the appended claims. Accordingly, the precedingmerely illustrates the principles of the invention. It will beappreciated that those skilled in the art will be able to devise variousarrangements, which, although not explicitly described or shown herein,embody the principles of the invention, and are included within itsspirit and scope. Furthermore, all examples and conditional languagerecited herein are principally intended to aid the reader inunderstanding the principles of the invention and the conceptscontributed by the inventors to furthering the art, and are to beconstrued as being without limitation to such specifically recitedexamples and conditions. Moreover, all statements herein recitingprinciples, aspects, and embodiments of the invention as well asspecific examples thereof, are intended to encompass both structural andfunctional equivalents thereof. Additionally, it is intended that suchequivalents include both currently known equivalents and equivalentsdeveloped in the future, i.e., any elements developed that perform thesame function, regardless of structure. The scope of the invention,therefore, is not intended to be limited to the exemplary embodimentsshown and described herein. It is intended that the following claimsdefine the scope of the invention and that methods and structures withinthe scope of these claims and their equivalents be covered thereby.

What is claimed is:
 1. A method, comprising: (i) calcining limestone toform lime wherein the lime comprises dead burnt lime and a gaseousstream comprising carbon dioxide; (ii) dissolving the lime in an aqueousN-containing inorganic salt solution to produce a first aqueous solutioncomprising calcium salt, and a gaseous stream comprising ammonia; (iii)recovering the gaseous stream comprising carbon dioxide and the gaseousstream comprising ammonia and subjecting the gaseous streams to acooling process to condense a second aqueous solution comprisingammonium bicarbonate, ammonium carbonate, ammonia, ammonium carbamate,or combination thereof; and (iv) treating the first aqueous solutioncomprising calcium salt with the second aqueous solution comprisingammonium bicarbonate, ammonium carbonate, ammonia, ammonium carbamate,or combination thereof to form a precipitation material comprisingcalcium carbonate, wherein the calcium carbonate comprises vaterite. 2.The method of claim 1, wherein the calcination is carried out in shaftkiln, rotary kiln, or electric kiln.
 3. The method of claim 1, whereinthe lime further comprises underburnt lime, soft burnt lime, orcombination thereof.
 4. The method of claim 1, wherein a N-containinginorganic salt in the aqueous N-containing inorganic salt solution isselected from the group consisting of ammonium halide, ammonium sulfate,ammonium sulfite, ammonium nitrate, ammonium nitrite, and combinationthereof.
 5. The method of claim 4, wherein the ammonium halide isammonium chloride.
 6. The method of claim 1, wherein a molar ratio of aN-containing inorganic salt in the aqueous N-containing inorganic saltsolution:lime is about 0.5:1-2:1.
 7. The method of claim 1, wherein thedissolving step is under one or more dissolution conditions selectedfrom the group consisting of temperature about 30-200° C.; pressureabout 0.1-10 atm; a N-containing inorganic salt wt % in water about0.5-50%; and combination thereof.
 8. The method of claim 1, wherein thegaseous stream comprising ammonia further comprises water vapor.
 9. Themethod of claim 1, wherein the cooling process is under one or morecooling conditions comprising temperature about 0-100° C.; pressureabout 0.5-50 atm; pH of the aqueous solution about 8-12; ratio ofCO₂:NH₃ about 0.1:1-20:1; or combination thereof.
 10. The method ofclaim 1, wherein the treating step is under one or more precipitationconditions selected from the group consisting of pH of the first aqueoussolution of 7-9, temperature of the solution of 20-60° C., residencetime of 5-60 minutes, and combination thereof.
 11. The method of claim1, wherein the first aqueous solution further comprises solid.
 12. Themethod of claim 11, further comprising separating the solid from thefirst aqueous solution before the treatment step by filtration and/orcentrifugation and adding the separated solid to the precipitationmaterial as filler.
 13. The method of claim 11, wherein the solid is notseparated from the first aqueous solution and the first aqueous solutionis subjected to the treatment step to produce the precipitation materialfurther comprising the solid.
 14. The method of claim 11, wherein thesolid comprises silicate, iron oxide, alumina, or combination thereof.15. The method of claim 1, wherein the vaterite is stable vaterite orreactive vaterite.
 16. The method of claim 15, further comprising addingwater to the precipitation material comprising reactive vaterite andtransforming the reactive vaterite to aragonite wherein the aragonitesets and hardens to form cement, cementitious product, non-cementitiousproduct, or combination thereof.
 17. The method of claim 16, wherein thecementitious product is aggregate; building material; or formed buildingmaterial selected from masonry unit, construction panel, conduit, basin,beam, column, slab, acoustic barrier, insulation material, andcombination thereof.
 18. The method of claim 1, wherein the firstaqueous solution further comprises dissolved ammonia.
 19. The method ofclaim 1, further comprising adding an additive to the first aqueoussolution, to the second aqueous solution, or to the precipitationmaterial, wherein the additive is selected from the group consisting offatty acid ester, sodium decyl sulfate, lauric acid, sodium salt oflauric acid, urea, citric acid, sodium salt of citric acid, phthalicacid, sodium salt of phthalic acid, taurine, creatine, dextrose,poly(n-vinyl-1-pyrrolidone), aspartic acid, sodium salt of asparticacid, magnesium chloride, acetic acid, sodium salt of acetic acid,glutamic acid, sodium salt of glutamic acid, strontium chloride, gypsum,lithium chloride, sodium chloride, glycine, sodium citrate dehydrate,sodium bicarbonate, magnesium sulfate, magnesium acetate, sodiumpolystyrene, sodium dodecylsulfonate, poly-vinyl alcohol, andcombination thereof.
 20. The method of claim 1, wherein the vaterite isunimodal, bimodal, or multimodal distribution of a particulatecomposition with an average particle size of between 0.1-100 micron. 21.The method of claim 1, further comprising blending the precipitationmaterial with Ordinary Portland Cement (OPC), aggregate, or combinationthereof.
 22. The method of claim 1, further comprising mixing theprecipitation material with an admixture selected from the groupconsisting of set accelerator, set retarder, air-entraining agent,foaming agent, defoamer, alkali-reactivity reducer, bonding admixture,dispersant, coloring admixture, corrosion inhibitor, damp-proofingadmixture, gas former, permeability reducer, pumping aid, shrinkagecompensation admixture, fungicidal admixture, germicidal admixture,insecticidal admixture, rheology modifying agent, finely divided mineraladmixture, pozzolan, aggregate, wetting agent, strength enhancing agent,water repellent, reinforced material, and combination thereof.
 23. Themethod of claim 22, wherein the reinforced material is a fiber made ofzirconia, aluminum, glass, steel, carbon, ceramic, grass, bamboo, wood,fiberglass, synthetic material, or combination thereof.